Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: bkorven on 01 August 2023, 21:19:50
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As I replaced suspension parts on my 1998 Omega B 2.0 16V, I tried removing the front ABS/wheel speed sensors. They broke, on both sides... and I learned that you simply do not remove them. ::) Note that the ABS-light was not on before the sensors were replaced.
After having installed everything, along with the new sensors, the ABS-light went on after having driven a few hundred meters.
The best deal I could find on new sensors was from USA. These sensors was specified to fit 1997 Cadillac Catera, but the OEM part number (90509421) matched. Could this be an issue?..
Measuring the sensors with a multimeter shows a resistance of ~1520 Ohm, on both sides. The sensors both react to waving a magnetic material past them. Rotating the wheel hubs slowly results in a voltage of 0.1-0.2 VDC, both sides, but it does not seem consistent.. I do not get any reading measuring ADC.
I have tried thoroughly cleaning the teeth on both wheel hubs.
I have tried connecting an ELM327 OBD, but it tells me that there is no communication with the ECU (the ELM327 works with other cars). I also tried getting codes by shorting pin 5 & 6 in the OBD-connector, but there is no flashing of codes (should ABS-related codes flash here as well?..).
I have had the battery negative terminal disconnected for a few minutes -> the ABS-light is on as soon as I connect it again and start the car.
I installed a coilover-kit on the car, which made it substantially lower than stock. But this should not be related, I suppose.
I suppose the problem have nothing to do with the rear wheel speed sensor, since the speedometer is working as normal.
Anyone have any ideas? Thanks in advance!
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(accidentally quoted myself when I was about to modify my original message, hence the reply)
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You suppose incorrectly on several points.
The sensors themselves are correct. The Speedo is driven by the ABS ECU, and whilst it is rumoured to use the front left sensor, speedometer issues point to a failed ECU rather than sensors. You need a proper Tech 2 to access the abs. Unless you can guarantee to spin the hubs evenly and consistently then you won't get a steady ready.
Fitting coil overs to an Omega is a waste of time,money and effort unless your aim is to make it undriveable.
As an aside, have you changed the wheels as part of this work?
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You suppose incorrectly on several points.
The sensors themselves are correct. The Speedo is driven by the ABS ECU, and whilst it is rumoured to use the front left sensor, speedometer issues point to a failed ECU rather than sensors. You need a proper Tech 2 to access the abs. Unless you can guarantee to spin the hubs evenly and consistently then you won't get a steady ready.
Fitting coil overs to an Omega is a waste of time,money and effort unless your aim is to make it undriveable.
As an aside, have you changed the wheels as part of this work?
Thanks for the response.
I see, I might get myself a Tech2.
No, I have not changed the wheels as part of this work.
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IF everything was ok regarding the abs before you changed the front sensors then it suggests an issue with the actual new sensors or the fitment of them.
are you 100% sure the connections are good.
are you 100% sure the new sensors are fully fitted into their recess and that no debris remains in the hole that could affect the reading in any way.
was the car switched on with the old damaged sensors in place ? could this have shorted / damaged the abs ecu ?
the abs light should come on initially and then go off whilst you are not moving proving the system thinks all is ok and then if it comes on once moving means it has detected an abnormality .
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IF everything was ok regarding the abs before you changed the front sensors then it suggests an issue with the actual new sensors or the fitment of them.
are you 100% sure the connections are good.
are you 100% sure the new sensors are fully fitted into their recess and that no debris remains in the hole that could affect the reading in any way.
was the car switched on with the old damaged sensors in place ? could this have shorted / damaged the abs ecu ?
the abs light should come on initially and then go off whilst you are not moving proving the system thinks all is ok and then if it comes on once moving means it has detected an abnormality .
I agree that it should reasonably be linked to the installation of the new sensors. Although I have found it strange that the light is on constantly, regardless of if the car is moving or not. And now you're confirming that it should not be that way, if it were only the sensors that give bad signals. That's good to know for certain, thanks.
Q: Am I 100% the connections are good?
A: No, but 99% sure. I haven't done much other than replace the sensors.
Q: Am I 100% sure the new sensors are fully fitted into their recess?
A: I have looked in between brake shield and the hub, and the gap seems to be very small. The distance is hard to measure, so I can't say for sure. I was hoping to be able to find this out by measuring the voltage while spinning the wheels.
Q: Is there any debris remaining in the hole that could affect the reading in any way?
A: Could be, yes. In order to fit the new sensors I had to sand the surfaces of the holes a little. I have cleaned the hubs carefully afterwards, but I guess I can't be 100% sure. Either way, this wouldn't explain the light being constantly on, would it?
Q: Was the car switched on with the old damaged sensors in place?
A: No, it was not. Would it be enough to only have the ignition on, to possibly have problems?
I am starting to believe the fault is somewhere else (perhaps with the ABS-ECU). I will see if I can get the error codes.
Thanks alot for your reply!
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to my understanding and assuming the ecu hasnt been damaged in any way the fact that the light comes on and stays on even before you are moving suggests that the ecu thinks there is a problem.i would double check the connections and even recheck the resistance readings .if you can read the circuit diag it might be worth reading the resistances at the abs ecu plug itself.
i dont have any front ones to hand to compare but my spare rear ones measure 1.5 k ohms.
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i dont have any front ones to hand to compare but my spare rear ones measure 1.5 k ohms.
...and measure the resistance to ground/shell/0V. This should be near infinite. A short between either terminal or the coil itself and the casing will cause the fault.
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I managed to fix the problem, and thought I would update the thread in case it can help someone else in the future.
In short, the problem was caused by:
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I managed to fix the problem, and thought I would update the thread in case it can help someone else in the future.
In short, the problem was caused by:
I somehow accidentally left the page with the just started reply, which I can no longer modify.
I managed to fix the problem, and thought I would update the thread in case it can help someone else in the future.
In short, the problem was caused by:
- Dirt and metal debris on the sensor(s)
- Incorrect sensor fitment (gap to reluctor ring too large, likely due to rust)
The active fault codes were:
- C0035-8 Front Left Wheel Sensor incorrect signal
- C0040-8 Front Right Wheel Sensor incorrect signal
- C0245-1 Wheel Sensor Signal Circuit out of nominal range/performance
Rotating the wheel at about 2 RPM, initially, the signal from one of the sensors would look like this (noisy and weak):
(https://i.ibb.co/nPCDVrv/measurement1.png) (https://ibb.co/MB6Rjn4)
After cleaning the sensor:
(https://i.ibb.co/vmyygJM/measurement2.png) (https://ibb.co/ctffMNs)
And after filing the hub, this is the best I could achieve:
(https://i.ibb.co/1stt1YD/measurement3.png) (https://ibb.co/FsLL2kS)
The ABS light went out as soon as I started the car and got rolling. What I find odd though, is that the signal gets stronger by rotating the sensor out of its intended alignment in the hole. While turning the sensor in the hole, I would find a sweet spot where I left it at. See pictures below, for original position and the position with stronger signal (~50mV AC vs ~200mV AC). This orientation of the sensor means that I can't attach it with the bolt, but it sits very tightly in the hole and won't move. It was the same on both sides.
(https://i.ibb.co/SJxmHhn/IMG-20230924-213352.jpg) (https://ibb.co/vDBdf7P)
Original position
(https://i.ibb.co/tDjvw6g/IMG-20230924-213249.jpg) (https://ibb.co/jD0Q9Ym)
Sweet spot
So make sure the sensors are clean and that the gap to reluctor ring is sufficiently small!
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You may find that the hubs require replacing as the reluctor ring on the fronts is part of the bearing assembly.
The magnet on the sensor will have field around it which is disturbed by the rotation of the hub. Moving the sensor away from its factory orientation may result in adverse abs performance.
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The ABS light went out as soon as I started the car and got rolling. What I find odd though, is that the signal gets stronger by rotating the sensor out of its intended alignment in the hole. While turning the sensor in the hole, I would find a sweet spot where I left it at. See pictures below, for original position and the position with stronger signal (~50mV AC vs ~200mV AC). This orientation of the sensor means that I can't attach it with the bolt, but it sits very tightly in the hole and won't move. It was the same on both sides.
(https://i.ibb.co/SJxmHhn/IMG-20230924-213352.jpg) (https://ibb.co/vDBdf7P)
Original position
(https://i.ibb.co/tDjvw6g/IMG-20230924-213249.jpg) (https://ibb.co/jD0Q9Ym)
Sweet spot
So make sure the sensors are clean and that the gap to reluctor ring is sufficiently small!
I've had exactly this problem and found exactly the same with a pattern sensor (Vemo). Wheel bearing had also been replaced (as you know reluctor part of bearing / hub assembly) at the same time. the 'sweet spot' worked fine but obviously can't be fixed as the bolt hole didn't line up. I managed to source a brand new, old stock genuine GM sensor from Germany and it's been fine ever since. :y
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brilliant .glad you sorted it.
and also its nice for someone like yourself to come on afterwards and say the problem has been fixed.so many forums give helpfull advice to people and you never hear a word after !
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You may find that the hubs require replacing as the reluctor ring on the fronts is part of the bearing assembly.
The magnet on the sensor will have field around it which is disturbed by the rotation of the hub. Moving the sensor away from its factory orientation may result in adverse abs performance.
I think you are right. I have noticed that the ABS sometimes activates when it should not. I tried returning the sensors to the original position, and the ABS light comes back on.
So next step will be to install new hubs with reluctor rings.
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The ABS light went out as soon as I started the car and got rolling. What I find odd though, is that the signal gets stronger by rotating the sensor out of its intended alignment in the hole. While turning the sensor in the hole, I would find a sweet spot where I left it at. See pictures below, for original position and the position with stronger signal (~50mV AC vs ~200mV AC). This orientation of the sensor means that I can't attach it with the bolt, but it sits very tightly in the hole and won't move. It was the same on both sides.
(https://i.ibb.co/SJxmHhn/IMG-20230924-213352.jpg) (https://ibb.co/vDBdf7P)
Original position
(https://i.ibb.co/tDjvw6g/IMG-20230924-213249.jpg) (https://ibb.co/jD0Q9Ym)
Sweet spot
So make sure the sensors are clean and that the gap to reluctor ring is sufficiently small!
I've had exactly this problem and found exactly the same with a pattern sensor (Vemo). Wheel bearing had also been replaced (as you know reluctor part of bearing / hub assembly) at the same time. the 'sweet spot' worked fine but obviously can't be fixed as the bolt hole didn't line up. I managed to source a brand new, old stock genuine GM sensor from Germany and it's been fine ever since. :y
That is very interesting! The signal on my car is still too weak in its original orientation, and I suspect the reluctor rings to be bad.
Will replace, and I'll get back with the results!
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brilliant .glad you sorted it.
and also its nice for someone like yourself to come on afterwards and say the problem has been fixed.so many forums give helpfull advice to people and you never hear a word after !
Thank you! Hehe, I've several times found myself reading similar threads on different topics where I have been dying to know about the outcome and what fixed a problem. I'm grateful for everyone trying to help out, so to come back with answers to what was wrong is the least I can do.
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not having a front one to hand to look at but i assume the design is physically similar to the rears .the sensor 'pick up area' is exactly in line with the mounting lug.i wonder if replacements are identical or could be off centre in any way ? explaining the rotation difference or the body depth is in any way slightly different.? as mentioned,replacing (or at least checking/cleaning) the toothed ring would at least make that part eliminated.
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Rears are a ring on the drive shaft and might be available separately.
Fronts are cut into the rear face of the front hub and can only be replaced as a complete front hub bearing and flange assembly.
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yes i realise that.i was just trying to offer some advice regarding the sensor orientation and operation.
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not having a front one to hand to look at but i assume the design is physically similar to the rears .the sensor 'pick up area' is exactly in line with the mounting lug.i wonder if replacements are identical or could be off centre in any way ? explaining the rotation difference or the body depth is in any way slightly different.? as mentioned,replacing (or at least checking/cleaning) the toothed ring would at least make that part eliminated.
I could not tell a difference between the replacement sensors and the ones I had before. The thought has crossed my mind, that there could be a slight difference, although the OEM number matches.
Either way, I am very excited to replace the hubs and perform new measurements. They were ordered today.
By the way; Haynes manual states the hub nut to be torqued to 320 Nm. That sounds extremely high. Thoughts on this? My biggest torque wrench goes to 210 Nm, and I'll probably turn it some extra degrees afterwards and be happy.
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210 is 65% of 320... it only holds the wheel on, so be prudent to obtain a torque wrench that can at least pretend to hit 320 Nm.
As an aside, if you go with your original idea, there's a reasonable chance that you overtighten the front hubs, causing the bearings to bind up once there's some heat in them. And that's a whole new level of inconvenience.
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.....
My biggest torque wrench goes to 210 Nm, and I'll probably turn it some extra degrees afterwards and be happy.
That exactly what the local garage said he'd done when I gave him a hub/bearing to fit to my Omega. I never had a subsequent problem
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overtightening theoretically can only strip or break the nut or thread. itwont actually overtighten the bearing as its 2 thrust bearings back to back and touching each other.
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I thought the front hub tightening is a 3 stage process (I haven't got the exact figures to hand as I'm not at home) -
1- tighten to ?? Nm (a relatively low figure capable of being attained with most torque wrenches)
2- angle tighten
3- angle tighten
That's how I did my last front hub change as per Haynes (I think)?
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No according to Haynes the hub nut is tightened to 320Nm/236lb/ft no angle tightening is involved.Angle tightening is mentioned for anti roll bar bearing bracket bolts,front subframe, lower suspension arm pivot bolts and strut to steering knuckle.
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No according to Haynes the hub nut is tightened to 320Nm/236lb/ft no angle tightening is involved.Angle tightening is mentioned for anti roll bar bearing bracket bolts,front subframe, lower suspension arm pivot bolts and strut to steering knuckle.
Yes, you are right Baza - my mistake.... The more I think about it (it was some years ago!) I actually changed the complete knuckle as a whole unit with the hub, as the original brake shields were rotten as a pear - I didn't actually remove / change the hub / bearing. The angle tightening sequence I mentioned was actually for the front strut bolts...::)
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overtightening theoretically can only strip or break the nut or thread. itwont actually overtighten the bearing as its 2 thrust bearings back to back and touching each other.
So are the front bearings on the S Class, except rather than tightening to a torque setting they are set to a specific amount of play at the hub face.
Point being, that they have a torque setting for a reason and 210 Nm plus a pinch of wishful thinking simply won't cut it.
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not having a front one to hand to look at but i assume the design is physically similar to the rears .the sensor 'pick up area' is exactly in line with the mounting lug.i wonder if replacements are identical or could be off centre in any way ? explaining the rotation difference or the body depth is in any way slightly different.? as mentioned,replacing (or at least checking/cleaning) the toothed ring would at least make that part eliminated.
I could not tell a difference between the replacement sensors and the ones I had before. The thought has crossed my mind, that there could be a slight difference, although the OEM number matches.
Either way, I am very excited to replace the hubs and perform new measurements. They were ordered today.
By the way; Haynes manual states the hub nut to be torqued to 320 Nm. That sounds extremely high. Thoughts on this? My biggest torque wrench goes to 210 Nm, and I'll probably turn it some extra degrees afterwards and be happy.
210 will be enough to let you drive it to a garage for a final torque-up with the right equipment.
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Thanks for all the replies.
Unfortunately, the problem persists. Now, though, I am almost completely certain it is all about signal strength.
The wheel hub assemblies were replaced in the front. And they were torqued to 320 Nm, according to specification ;) New reluctor rings gave no improvement.
(https://i.ibb.co/Zd3Rj4K/IMG-20231023-193748.jpg) (https://ibb.co/CBqpcCv)
(https://i.ibb.co/gVLkX7k/IMG-20231023-193820.jpg) (https://ibb.co/k1sNryN)
(https://i.ibb.co/LRqPHDw/IMG-20231023-194028.jpg) (https://ibb.co/KhQGScZ)
By rotating the sensors inside their mounting hole on the steering knuckle, and thus varying the signal strength for some reason, I have found that at what speed ABS is activated seems directly proportional. "Sweet spot" leads to the ABS activating just before coming to a stop, at perhaps 5 km/h. The closer I rotate the sensors back to their original position, the higher the speed at which ABS starts intervening. And with the sensors in their original position, ABS-light also comes on.
Note that front left and front right sensor seem to perform identically.
So my reflections right now are:
- Could the signal be weak due to bad connection to ground?
- Do front left and front right wheel speed sensors share ground?
- Why would this problem arise after replacing front suspension along with new sensors?
This is the only ground I've found under the hood. Can someone confirm if this could be where the sensors ground?:
(https://i.ibb.co/71ZVXb6/IMG-20231024-221740.jpg) (https://ibb.co/LZc68v2)
(https://i.ibb.co/v3RqQKS/IMG-20231024-221800.jpg) (https://ibb.co/9bSgVC7)
I guess my next step will be to check wiring, and I'll also test supplying a new temporary ground.
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I've only played with Carlton/Senator ABS, not Omega B, and it might be different - but.....
There is no ground on the sensors. The two sensor wires are differential all the way to the control unit. Infact the resistance to ground of both terminals is many hundreds of K-ohms. If either terminal is somehow shorted to ground, the ABS fault light comes on.
As I say - on the Carlton/Senator.
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Position of the sensor head both in depth and orientation will affect the magnetic field and thus the reading and operation of the ABS.
The sensor magnet should be oriented parallel to the reluctor face.
Another consideration is that the number of notches on the reluctor ring face is identical to the original and likewise the magnetic tip of an aftermarket sensor.
The owners manual should give the operating parameters of the ABS as a system as it doesn't function across the entire speed envelope.
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Position of the sensor head both in depth and orientation ...
The sensor magnet should be oriented parallel to the reluctor face.
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Orientation mentioned first, as in the rotation against the teeth in addition to just as in how parallel it is, as mentioned afterwards?
I wonder if by rotating the sensors, I am affecting how parallel they are towards the reluctor rings, and thus affecting the signal strength. Which also makes me wonder if new steering knuckles would solve my problem. But I highly doubt it.
Right now the sensors are barely touching the rings, so the depth should be excluded as a possible cause.
Thinking out loud:
Are the mounting surfaces for the sensors om my steering knuckles not flat/even enough? Is there a reasonable probability that this problem could be exactly the same on both sides?
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I've only played with Carlton/Senator ABS, not Omega B, and it might be different - but.....
There is no ground on the sensors. The two sensor wires are differential all the way to the control unit. Infact the resistance to ground of both terminals is many hundreds of K-ohms. If either terminal is somehow shorted to ground, the ABS fault light comes on.
As I say - on the Carlton/Senator.
Thank you! That is valuable information.
I have measured the resistance of the terminals to 6.8M Ohm on both sides, and I assume that reading is OK.
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Position of the sensor head both in depth and orientation ...
The sensor magnet should be oriented parallel to the reluctor face.
...
Orientation mentioned first, as in the rotation against the teeth in addition to just as in how parallel it is, as mentioned afterwards?
Yes
I wonder if by rotating the sensors, I am affecting how parallel they are towards the reluctor rings, and thus affecting the signal strength. Exactly this. Which also makes me wonder if new steering knuckles would solve my problem Waste of money. But I highly doubt it.
The new bearing assembly and the sensor could both be the cause, especially if cheap parts have been used.
Right now the sensors are barely touching the rings, so the depth should be excluded as a possible cause.
Thinking out loud:
Are the mounting surfaces for the sensors om my steering knuckles not flat/even enough? Is there a reasonable probability that this problem could be exactly the same on both sides?
To your first point, I did suggest this when you first raised the question ;)
To your last point, it's possible that the new sensors are a cheap impression of the genuine article and are totally out of shape. In fact, because you ended up fitting them clocked away from the bolt holes, the chances are that they are basically junk.
A genuine sensor should fit into the knuckle precisely and it's extremely unlikely that the hole in the knuckle is distorted.
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The best deal I could find on new sensors was from USA. These sensors was specified to fit 1997 Cadillac Catera, but the OEM part number (90509421) matched. Could this be an issue?..
Were the Cadillac ABS sensors genuine GM or were they third party?
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I've only played with Carlton/Senator ABS, not Omega B, and it might be different - but.....
There is no ground on the sensors. The two sensor wires are differential all the way to the control unit. Infact the resistance to ground of both terminals is many hundreds of K-ohms. If either terminal is somehow shorted to ground, the ABS fault light comes on.
As I say - on the Carlton/Senator.
Thank you! That is valuable information.
I have measured the resistance of the terminals to 6.8M Ohm on both sides, and I assume that reading is OK.
Yes, that sounds about right.
The sensors are called variable reluctance sensor. Their output signal amplitude is a function of both RPM and clearance. You seem to be saying that by rotating the sensor things get better/worse. Note that the clearance is important - if the sensor is too close to the reluctor ring then it'll generate too high voltage, and this can upset the control unit. Rotating the sensor will reduce the amplitude as the 'blade' of the sensor becomes mis-aligned with the teeth on the reluctor ring..
So check the clearance between the tip of the sensor and the reluctor ring on the wheel bearing. I don't know what it is supposed to be, but I'd expect something like 1mm-2mm. You say up thread that it is (almost?) touching. That isn't correct. If it is, then the sensors are wrong but you might be able to correct it by putting shims in between the sensor and the steering knuckle.
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Position of the sensor head both in depth and orientation ...
The sensor magnet should be oriented parallel to the reluctor face.
...
Orientation mentioned first, as in the rotation against the teeth in addition to just as in how parallel it is, as mentioned afterwards?
Yes
I wonder if by rotating the sensors, I am affecting how parallel they are towards the reluctor rings, and thus affecting the signal strength. Exactly this. Which also makes me wonder if new steering knuckles would solve my problem Waste of money. But I highly doubt it.
The new bearing assembly and the sensor could both be the cause, especially if cheap parts have been used.
Right now the sensors are barely touching the rings, so the depth should be excluded as a possible cause.
Thinking out loud:
Are the mounting surfaces for the sensors om my steering knuckles not flat/even enough? Is there a reasonable probability that this problem could be exactly the same on both sides?
To your first point, I did suggest this when you first raised the question ;)
To your last point, it's possible that the new sensors are a cheap impression of the genuine article and are totally out of shape. In fact, because you ended up fitting them clocked away from the bolt holes, the chances are that they are basically junk.
A genuine sensor should fit into the knuckle precisely and it's extremely unlikely that the hole in the knuckle is distorted.
The signal strength was unaffected by installing the new bearing assemblies, so they are not the cause.
The sensors might be crap. In that case, I consider myself to have been scammed. The seller could honestly just as well have sent me an empty box, and it wouldn't be any different from receiving a dysfunctional product. In fact, that would actually have saved me time, money and hassle. Sigh... let's hope it's not the sensors. I don't know how to confirm that without committing to buying new ones.
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The best deal I could find on new sensors was from USA. These sensors was specified to fit 1997 Cadillac Catera, but the OEM part number (90509421) matched. Could this be an issue?..
Were the Cadillac ABS sensors genuine GM or were they third party?
The sensors are of the brand "Holstein", part number "2ABS1206". I don't know for sure what brand the sensors has from factory.
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I've only played with Carlton/Senator ABS, not Omega B, and it might be different - but.....
There is no ground on the sensors. The two sensor wires are differential all the way to the control unit. Infact the resistance to ground of both terminals is many hundreds of K-ohms. If either terminal is somehow shorted to ground, the ABS fault light comes on.
As I say - on the Carlton/Senator.
Thank you! That is valuable information.
I have measured the resistance of the terminals to 6.8M Ohm on both sides, and I assume that reading is OK.
Yes, that sounds about right.
The sensors are called variable reluctance sensor. Their output signal amplitude is a function of both RPM and clearance. You seem to be saying that by rotating the sensor things get better/worse. Note that the clearance is important - if the sensor is too close to the reluctor ring then it'll generate too high voltage, and this can upset the control unit. Rotating the sensor will reduce the amplitude as the 'blade' of the sensor becomes mis-aligned with the teeth on the reluctor ring..
So check the clearance between the tip of the sensor and the reluctor ring on the wheel bearing. I don't know what it is supposed to be, but I'd expect something like 1mm-2mm. You say up thread that it is (almost?) touching. That isn't correct. If it is, then the sensors are wrong but you might be able to correct it by putting shims in between the sensor and the steering knuckle.
I estimate the distance to be somewhere around 0.2-0.3 mm at the moment. But the signal is too weak, and not the other way around. I don't know what the voltage should be specifically for the Omega, but reading online it seems to usually be between 0.5-1 V at 2 RPM of the wheel. I get ~50mV when the sensors are mounted in their intended position as from factory, and I can manage to get ~200mV when I rotate them.
The stronger I manage to get the signal (by rotating), the better the behaviour of the ABS.
The reason ABS is activated is likely due to the signal being too weak to be registrated by the ECU, so that it is interpreted as the wheels locking up.
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Sounds to me like the wrong sensors. EPC doesn't show the OEM part number, but most braking stuff on large Vauxhall/Opels is Bosch. Certainly is Bosch on Carlton/Senator.
I've never heard of Holstein (except as a cheap Beer here in the UK, and as a state in Germany)
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on all the evidence this would appear to be the problem. after all everything was ok untill you replaced the sensors. other parts worked on the original sensors .when you said you had got new ones i think we assumed you had found oem ones albeit for the caddy.
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Sounds to me like the wrong sensors. EPC doesn't show the OEM part number, but most braking stuff on large Vauxhall/Opels is Bosch. Certainly is Bosch on Carlton/Senator.
I've never heard of Holstein (except as a cheap Beer here in the UK, and as a state in Germany)
They are a Florida based reseller of third party manufactured parts.
I suspect that these sensors were purchased on price. And at risk of repeating myself. Again. If a part doesn't bolt straight in and/or appears different in anyway to the factory original, then it is unlikely to function correctly. Especially if it's electrical.
Buy a pair of genuine sensors, fit them and report back.
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Position of the sensor head both in depth and orientation ...
The sensor magnet should be oriented parallel to the reluctor face.
...
Orientation mentioned first, as in the rotation against the teeth in addition to just as in how parallel it is, as mentioned afterwards?
Yes
I wonder if by rotating the sensors, I am affecting how parallel they are towards the reluctor rings, and thus affecting the signal strength. Exactly this. Which also makes me wonder if new steering knuckles would solve my problem Waste of money. But I highly doubt it.
The new bearing assembly and the sensor could both be the cause, especially if cheap parts have been used.
Right now the sensors are barely touching the rings, so the depth should be excluded as a possible cause.
Thinking out loud:
Are the mounting surfaces for the sensors om my steering knuckles not flat/even enough? Is there a reasonable probability that this problem could be exactly the same on both sides?
To your first point, I did suggest this when you first raised the question ;)
To your last point, it's possible that the new sensors are a cheap impression of the genuine article and are totally out of shape. In fact, because you ended up fitting them clocked away from the bolt holes, the chances are that they are basically junk.
A genuine sensor should fit into the knuckle precisely and it's extremely unlikely that the hole in the knuckle is distorted.
The signal strength was unaffected by installing the new bearing assemblies, so they are not the cause.
The sensors might be crap. In that case, I consider myself to have been scammed. The seller could honestly just as well have sent me an empty box, and it wouldn't be any different from receiving a dysfunctional product. In fact, that would actually have saved me time, money and hassle. Sigh... let's hope it's not the sensors. I don't know how to confirm that without committing to buying new ones.
You missed my point re the bearings... If the reluctor teeth are different in number, size or shape to the factory originals, then they will cause an error even if the signal strength is consistent. The ECU will be looking for a specific number of teeth and if there's a mismatch between wheels or axles, then it won't function correctly. The sensors are a different issue, but both will cause faulty performance, and you've already admitted thet the sensors don't fit as you can't fit the retaining bolts. Which means that the sensors are free to move both rotationally and in/out along the casting. They're bolted for a reason.
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I've only played with Carlton/Senator ABS, not Omega B, and it might be different - but.....
There is no ground on the sensors. The two sensor wires are differential all the way to the control unit. Infact the resistance to ground of both terminals is many hundreds of K-ohms. If either terminal is somehow shorted to ground, the ABS fault light comes on.
As I say - on the Carlton/Senator.
Thank you! That is valuable information.
I have measured the resistance of the terminals to 6.8M Ohm on both sides, and I assume that reading is OK.
Yes, that sounds about right.
The sensors are called variable reluctance sensor. Their output signal amplitude is a function of both RPM and clearance. You seem to be saying that by rotating the sensor things get better/worse. Note that the clearance is important - if the sensor is too close to the reluctor ring then it'll generate too high voltage, and this can upset the control unit. Rotating the sensor will reduce the amplitude as the 'blade' of the sensor becomes mis-aligned with the teeth on the reluctor ring..
So check the clearance between the tip of the sensor and the reluctor ring on the wheel bearing. I don't know what it is supposed to be, but I'd expect something like 1mm-2mm. You say up thread that it is (almost?) touching. That isn't correct. If it is, then the sensors are wrong but you might be able to correct it by putting shims in between the sensor and the steering knuckle.
I estimate the distance to be somewhere around 0.2-0.3 mm at the moment. But the signal is too weak, and not the other way around. I don't know what the voltage should be specifically for the Omega, but reading online it seems to usually be between 0.5-1 V at 2 RPM of the wheel. I get ~50mV when the sensors are mounted in their intended position as from factory, and I can manage to get ~200mV when I rotate them.
The stronger I manage to get the signal (by rotating), the better the behaviour of the ABS.
The reason ABS is activated is likely due to the signal being too weak to be registrated by the ECU, so that it is interpreted as the wheels locking up.
Have you ground or filed the surface that the sensor sits on ,to make the sensor CLOSER to the reluctor ring :o
the surface looks way too flat and clean compared to the rest of the casting in your image
(https://i.ibb.co/tDjvw6g/IMG-20230924-213249.jpg)
have you tried shimming the sensor out ,to see how that effects the signal :-\
though i suspect the after market sensors may be the issue .
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Sounds to me like the wrong sensors. EPC doesn't show the OEM part number, but most braking stuff on large Vauxhall/Opels is Bosch. Certainly is Bosch on Carlton/Senator.
I've never heard of Holstein (except as a cheap Beer here in the UK, and as a state in Germany)
Also where much of your milk emanates from, moo. ;) ;D
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To Dave's last... That surface just looks clean, but the sensor is clearly clocked wrong. Ergo it is wrong and won't work correctly.
The magnet is, or should be, the size of the teeth on the reluctor. If it is clocked even a few degrees it will cover more than one tooth and therefore not pick up every space. Effective this fools it into see less teeth and therefore presuming the wheels are locking up. If the rear sensors are reading correctly then the ABS over reacts even more due to the fact that it thinks the front wheels are rotating at half the speed.
Undo everything you have done with actual genuine sensors and the system will work perfectly.
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If a part doesn't bolt straight in and/or appears different in anyway to the factory original, then it is unlikely to function correctly. Especially if it's electrical.
You missed my point re the bearings... If the reluctor teeth are different in number, size or shape to the factory originals, then they will cause an error even if the signal strength is consistent. The ECU will be looking for a specific number of teeth and if there's a mismatch between wheels or axles, then it won't function correctly. The sensors are a different issue, but both will cause faulty performance, and you've already admitted thet the sensors don't fit as you can't fit the retaining bolts. Which means that the sensors are free to move both rotationally and in/out along the casting. They're bolted for a reason.
Oh okay, I see. If the reluctor teeth would be that different from the stock ones, I'd find it startling to be honest. Am I naive to believe that parts that are sold should work? Anyways, I'm quite sure the bearing assemblies are OK. The dimensions and number of teeth was stated, and was the same for all different brands of bearing assemblies. I suppose it's harder with sensors, since they don't really state the number of windings inside them, or other such detailed information about the performance.
Although I guess it doesn't have any greater relevance to the discussion, just to clarify; the aftermarket sensors does fit perfectly. The signal is just too weak, and by rotating them it gets stronger.
To Dave's last... That surface just looks clean, but the sensor is clearly clocked wrong. Ergo it is wrong and won't work correctly.
The magnet is, or should be, the size of the teeth on the reluctor. If it is clocked even a few degrees it will cover more than one tooth and therefore not pick up every space. Effective this fools it into see less teeth and therefore presuming the wheels are locking up. If the rear sensors are reading correctly then the ABS over reacts even more due to the fact that it thinks the front wheels are rotating at half the speed.
Undo everything you have done with actual genuine sensors and the system will work perfectly.
While your reasoning with the magnet seeing more than one teeth at the same time in a rotated position sounds reasonable, the ABS-behaviour was actually improved by rotating the sensors away from the original position. I could not tell the frequency of the signal was affected, either.
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I've only played with Carlton/Senator ABS, not Omega B, and it might be different - but.....
There is no ground on the sensors. The two sensor wires are differential all the way to the control unit. Infact the resistance to ground of both terminals is many hundreds of K-ohms. If either terminal is somehow shorted to ground, the ABS fault light comes on.
As I say - on the Carlton/Senator.
Thank you! That is valuable information.
I have measured the resistance of the terminals to 6.8M Ohm on both sides, and I assume that reading is OK.
Yes, that sounds about right.
The sensors are called variable reluctance sensor. Their output signal amplitude is a function of both RPM and clearance. You seem to be saying that by rotating the sensor things get better/worse. Note that the clearance is important - if the sensor is too close to the reluctor ring then it'll generate too high voltage, and this can upset the control unit. Rotating the sensor will reduce the amplitude as the 'blade' of the sensor becomes mis-aligned with the teeth on the reluctor ring..
So check the clearance between the tip of the sensor and the reluctor ring on the wheel bearing. I don't know what it is supposed to be, but I'd expect something like 1mm-2mm. You say up thread that it is (almost?) touching. That isn't correct. If it is, then the sensors are wrong but you might be able to correct it by putting shims in between the sensor and the steering knuckle.
I estimate the distance to be somewhere around 0.2-0.3 mm at the moment. But the signal is too weak, and not the other way around. I don't know what the voltage should be specifically for the Omega, but reading online it seems to usually be between 0.5-1 V at 2 RPM of the wheel. I get ~50mV when the sensors are mounted in their intended position as from factory, and I can manage to get ~200mV when I rotate them.
The stronger I manage to get the signal (by rotating), the better the behaviour of the ABS.
The reason ABS is activated is likely due to the signal being too weak to be registrated by the ECU, so that it is interpreted as the wheels locking up.
Have you ground or filed the surface that the sensor sits on ,to make the sensor CLOSER to the reluctor ring :o
the surface looks way too flat and clean compared to the rest of the casting in your image
(https://i.ibb.co/tDjvw6g/IMG-20230924-213249.jpg)
have you tried shimming the sensor out ,to see how that effects the signal :-\
though i suspect the after market sensors may be the issue .
Yes, I have filed the surface that the sensor sits on. It was an attempt to make the signal stronger... and a successful one at that ;D
In my desperate troubleshooting I saw a possible cause of the problem that corrosion had increased the clearance.
I have tested the signal with a larger distance from the reluctor ring, yes. The signal gets weaker, as expected.
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Which just goes to show that the sensors are wrong.
You might try fitting them in the correct position, and see if the driveability improves.
The sensors might work electrically but the information they are sending to the ABS ECU is clearly not right.
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Thanks for all the input, from all of you! I really appreciate it.
It seems highly likely that the sensors are bad, after all. I actually did not know the sensors I had ordered were not genuine OEM. The brand of the ones I ordered was pretty well hidden under an "extra info"-tab that needed to be opened to show. It would have been better if I had provided you with information about the manufacturer early on, ofcourse.
I'll order new ones, and will report back with the result.
The problem now is that the only sensors that seem reasonable, that I seem to be able to get online, are of brand "Vemo", model "V40-72-0472". No genuine sensors anywhere to be found. Just alot of other shady "beer"-named ones and similar.
I think I'll just do it the old way, and give my local Opel-dealer a call on Monday.
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Which just goes to show that the sensors are wrong.
You might try fitting them in the correct position, and see if the driveability improves.
The sensors might work electrically but the information they are sending to the ABS ECU is clearly not right.
Might indicate that they are wrong. Not 100% certain of that.
I have tried fitting them in the correct position. It gets worse, and the ABS-light comes on again.
I agree with you about that, the information they are sending is definitely not right.
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Both the frequency AND amplitude of the sensor output will increase with RPM. You say you are measuring at 2 RPM. Assuming you're using 235R45x17 tyres, the rolling circumference is 79.57 inches (2021mm). 2 RPM is 120 revs per hour, which is therefore 9548 inches per hour, which is only 0.15 miles per hour.
I don't think the ABS is supposed to work at all below 5mph. Therefore the voltages you are seeing from the sensors are not representative of what you should see if the car is travelling at > 5MPH (8 Km/h).
Your 50mV at 2RPM might be correct - Try it again at a more realistic 200RPM (15 MPH), you should get a much larger signal - probably 20-50 times larger. Remember the ABS needs to work all the way up to above top speed (say 2000RPM/150MPH) so the signal can be massive at that speed. If you adjusts the sensors to give large signals at very low speeds, then at normal/high speed you can overload the ABS inputs.
I've got some old Carlton hubs in the lockup, still with the ABS sensors fitted. I'll dig them out tomorrow and measure them up for clearance. 0.2-0.3mm sounds way too close to me.
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Both the frequency AND amplitude of the sensor output will increase with RPM. You say you are measuring at 2 RPM. Assuming you're using 235R45x17 tyres, the rolling circumference is 79.57 inches (2021mm). 2 RPM is 120 revs per hour, which is therefore 9548 inches per hour, which is only 0.15 miles per hour.
I don't think the ABS is supposed to work at all below 5mph. Therefore the voltages you are seeing from the sensors are not representative of what you should see if the car is travelling at > 5MPH (8 Km/h).
Your 50mV at 2RPM might be correct - Try it again at a more realistic 200RPM (15 MPH), you should get a much larger signal - probably 20-50 times larger. Remember the ABS needs to work all the way up to above top speed (say 2000RPM/150MPH) so the signal can be massive at that speed. If you adjusts the sensors to give large signals at very low speeds, then at normal/high speed you can overload the ABS inputs.
I've got some old Carlton hubs in the lockup, still with the ABS sensors fitted. I'll dig them out tomorrow and measure them up for clearance. 0.2-0.3mm sounds way too close to me.
I'm comparing my voltage at 2 RPM to what others have measured at that same speed, so what voltage the sensors generate at higher speeds is not really of relevance for that matter. I'm expecting 0.5V-1V at 2 RPM, but I'm measuring much lower than that at 2 RPM.
Overload the ABS-inputs, as in causing damage, or as in disrupt the function? I assume there is binary switching inside the ECU, for a threshold value of the signal. In that case, the signal just needs to be strong enough, and all that matters is frequency/consistency of the signal. I could be (and probably am) wrong.
I am convinced that 0.2-0.3mm is a shorter distance than what it was originally, but I'm not convinced the distance can be too short. I also still believe my signal is too weak.
Either way, I'm grateful for you for taking the time to check it out.
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Perhaps you are over thinkng the whole thing.
Given that the system doesn't work correctly with those sensors and that the sensors don't fit correctly, the simple fact is that you need the correct sensors. And possibly bearing assemblies. (Omega A and Omega B hubs may seem to be similar, but that doesn't guarantee that they are the same and it would be all too easy for the parts suppliers to make the same assumption).
Anything else is a waste of time and effort unless you're retired and extremely bored.
Trying to position the wrong sensors in the correct position is akin to trying to make a rear door fit the front door aperture... You might make it latch, but it will never function correctly.
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Both the frequency AND amplitude of the sensor output will increase with RPM. You say you are measuring at 2 RPM. Assuming you're using 235R45x17 tyres, the rolling circumference is 79.57 inches (2021mm). 2 RPM is 120 revs per hour, which is therefore 9548 inches per hour, which is only 0.15 miles per hour.
I don't think the ABS is supposed to work at all below 5mph. Therefore the voltages you are seeing from the sensors are not representative of what you should see if the car is travelling at > 5MPH (8 Km/h).
Your 50mV at 2RPM might be correct - Try it again at a more realistic 200RPM (15 MPH), you should get a much larger signal - probably 20-50 times larger. Remember the ABS needs to work all the way up to above top speed (say 2000RPM/150MPH) so the signal can be massive at that speed. If you adjusts the sensors to give large signals at very low speeds, then at normal/high speed you can overload the ABS inputs.
I've got some old Carlton hubs in the lockup, still with the ABS sensors fitted. I'll dig them out tomorrow and measure them up for clearance. 0.2-0.3mm sounds way too close to me.
I'm comparing my voltage at 2 RPM to what others have measured at that same speed, so what voltage the sensors generate at higher speeds is not really of relevance for that matter. I'm expecting 0.5V-1V at 2 RPM, but I'm measuring much lower than that at 2 RPM.
Overload the ABS-inputs, as in causing damage, or as in disrupt the function? I assume there is binary switching inside the ECU, for a threshold value of the signal. In that case, the signal just needs to be strong enough, and all that matters is frequency/consistency of the signal. I could be (and probably am) wrong.
I am convinced that 0.2-0.3mm is a shorter distance than what it was originally, but I'm not convinced the distance can be too short. I also still believe my signal is too weak.
Either way, I'm grateful for you for taking the time to check it out.
The hall sensor on a square cut reluctor wheel produces a binary signal, it's either on or off. The frequency relative to the other sensors is what makes the whole thing work. It might be intelligent enough to allow for steering input ie slower wheel speeds on one side of the car vs the other.
If the ECU receives anything other the the expected on/off then it presumes there is an issue and behaves accordingly.
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Incidentally, what hubs did you fit? Whilst they are both have 48 teeth, they look very different in your photo. The new reluctor face looks to be off centre.
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Incidentally, what hubs did you fit? Whilst they are both have 48 teeth, they look very different in your photo. The new reluctor face looks to be off centre.
These are the hubs I ordered: https://www.autodoc.co.uk/ridex/8054400
And these are the hubs I received, which is not what I ordered: https://www.buycarparts.co.uk/esen-skv/18164200
I suspect that one manufacturer produces parts for several brands, and the only difference is the logo on the box.
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Perhaps you are over thinkng the whole thing.
Given that the system doesn't work correctly with those sensors and that the sensors don't fit correctly, the simple fact is that you need the correct sensors. And possibly bearing assemblies. (Omega A and Omega B hubs may seem to be similar, but that doesn't guarantee that they are the same and it would be all too easy for the parts suppliers to make the same assumption).
Anything else is a waste of time and effort unless you're retired and extremely bored.
Trying to position the wrong sensors in the correct position is akin to trying to make a rear door fit the front door aperture... You might make it latch, but it will never function correctly.
I definitely agree. I'll order new sensors on Monday.
P.S.: And I hope I won't need to order new bearing assemblies as well.
Both the frequency AND amplitude of the sensor output will increase with RPM. You say you are measuring at 2 RPM. Assuming you're using 235R45x17 tyres, the rolling circumference is 79.57 inches (2021mm). 2 RPM is 120 revs per hour, which is therefore 9548 inches per hour, which is only 0.15 miles per hour.
I don't think the ABS is supposed to work at all below 5mph. Therefore the voltages you are seeing from the sensors are not representative of what you should see if the car is travelling at > 5MPH (8 Km/h).
Your 50mV at 2RPM might be correct - Try it again at a more realistic 200RPM (15 MPH), you should get a much larger signal - probably 20-50 times larger. Remember the ABS needs to work all the way up to above top speed (say 2000RPM/150MPH) so the signal can be massive at that speed. If you adjusts the sensors to give large signals at very low speeds, then at normal/high speed you can overload the ABS inputs.
I've got some old Carlton hubs in the lockup, still with the ABS sensors fitted. I'll dig them out tomorrow and measure them up for clearance. 0.2-0.3mm sounds way too close to me.
I'm comparing my voltage at 2 RPM to what others have measured at that same speed, so what voltage the sensors generate at higher speeds is not really of relevance for that matter. I'm expecting 0.5V-1V at 2 RPM, but I'm measuring much lower than that at 2 RPM.
Overload the ABS-inputs, as in causing damage, or as in disrupt the function? I assume there is binary switching inside the ECU, for a threshold value of the signal. In that case, the signal just needs to be strong enough, and all that matters is frequency/consistency of the signal. I could be (and probably am) wrong.
I am convinced that 0.2-0.3mm is a shorter distance than what it was originally, but I'm not convinced the distance can be too short. I also still believe my signal is too weak.
Either way, I'm grateful for you for taking the time to check it out.
The hall sensor on a square cut reluctor wheel produces a binary signal, it's either on or off. The frequency relative to the other sensors is what makes the whole thing work. It might be intelligent enough to allow for steering input ie slower wheel speeds on one side of the car vs the other.
If the ECU receives anything other the the expected on/off then it presumes there is an issue and behaves accordingly.
My Omega does not have hall sensors, they are variable reluctance sensors. They are passive, and the signal they generate from the reluctor ring is a sinus wave (see my attached images in my earlier post). The ECU probably just monitors the passing of a threshold value for the voltage.
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That's a mistake on my part but the principle stands.
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EPC says that Omega A, Senator B & Omega B/B2 all use the same front hub assembly, GM# 90486467 / Opel KAT# 16-03-194. Not carried forward onto newer GM models.
And you're right, it's very likely that there is only one source supplying the hub assemblies and they are rebranded with whatever the buyer requests. It's also very likely that actual production ceased years ago and that anything available of whatever brand is actually old stock, dumped on the market to the highest bidder or bought up by old stock specialists. There are simply not enough Omegas or Cateras left to make it worthwhile for anyone to tool-up and manufacture any new parts.
The Ridex parts you ordered and the ESEN-SKV parts you received should be equivalent to each other and the factory fit and should work.
How did you clean out the bores for the sensors?
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https://www.ebay.co.uk/itm/314827804947
https://www.ebay.co.uk/itm/295477250260
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Perhaps you are over thinkng the whole thing.
Given that the system doesn't work correctly with those sensors and that the sensors don't fit correctly, the simple fact is that you need the correct sensors. And possibly bearing assemblies. (Omega A and Omega B hubs may seem to be similar, but that doesn't guarantee that they are the same and it would be all too easy for the parts suppliers to make the same assumption).
Anything else is a waste of time and effort unless you're retired and extremely bored.
Trying to position the wrong sensors in the correct position is akin to trying to make a rear door fit the front door aperture... You might make it latch, but it will never function correctly.
I've never looked at the electronics inside an ABS control unit. If I had to guess I'd say the differential input goes into a balanced op amp which converts the sine wave to a digital input. But that's a guess.
The issue with reluctance sensors is that their voltage output is very frequency dependent. Given that the system is supposed to work from 5MPH to 150MPH there will be a very large variation in the signal amplitude at these two extremes - small at low speeds, very large (as in hundreds of volts) at high speed. I'll try and set it up in a bench drill to measure/demonstrate tomorrow.
But the point is the system will be setup to work reliably from 5mph to 150mph with standard clearances. If you move the sensor too close, it may overload the system at higher speeds - I know this is an issue with the Lotus Carlton ignition sensor, which is also a variable reluctance sensor. If the gap is too small, the ignition module misfires at high RPM due to being overloaded. The cure is to put in shims to space the sensor away from the timing wheel - there is a field service note in the dealer manual to do with this. It's unlikely to cause damage inside the control unit, but it can cause mis-triggers. The LC timing sensor spacing is specced at 1.5mm gap. The ABS sensors are similar, and 0.2-0.3mm clearance doesn't sound right to me.
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Incidentally, the Febi hub linked to above does at least look like the original part as displayed in your side by side picture.
And to Malcolm's last, that's a moot point given that the sensors clearly don't work or fit correctly.
The depth at which they're set is arguably as important as the orientation of the sensor head.
Actual live data from the ABS ECU would confirm the signal difference compared to the rears and highlight the specific fault codes. But that would only confirm what we know from the first post...
The new sensors are faulty. Whether that's by design or accident doesn't really matter, the net result is the same.
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Buying second hand ,genuine knuckles with genuine ABS sensors would be a way back to working ABS
not cheap though as you'd have to fit them, then get an alignment :(
what happened to the original sensors ???
I purchased low mile Omega B2 hubs/sensors as spares when i had omega As (Vauxhall Carltons) years ago :)
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Buying second hand ,genuine knuckles with genuine ABS sensors would be a way back to working ABS
not cheap though as you'd have to fit them, then get an alignment :(
what happened to the original sensors ???
I purchased low mile Omega B2 hubs/sensors as spares when i had omega As (Vauxhall Carltons) years ago :)
Yep! New sensors will be ordered. But I think I use the old knuckles, and use some material inbetween to increase the distance if needed.
I don't mind the fitting, as I do all the work on my car myself in my garage. Since I've replaced suspension I'll need an alignment regardless. So that's OK!
The original sensors broke as I tried removing them, while replacing suspension parts. The Haynes book stated to do so, but it would not have been necessary. All of the problems I have with the ABS is just an unlucky side effect from wanting to replace suspension parts.
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Perhaps you are over thinkng the whole thing.
Given that the system doesn't work correctly with those sensors and that the sensors don't fit correctly, the simple fact is that you need the correct sensors. And possibly bearing assemblies. (Omega A and Omega B hubs may seem to be similar, but that doesn't guarantee that they are the same and it would be all too easy for the parts suppliers to make the same assumption).
Anything else is a waste of time and effort unless you're retired and extremely bored.
Trying to position the wrong sensors in the correct position is akin to trying to make a rear door fit the front door aperture... You might make it latch, but it will never function correctly.
I've never looked at the electronics inside an ABS control unit. If I had to guess I'd say the differential input goes into a balanced op amp which converts the sine wave to a digital input. But that's a guess.
The issue with reluctance sensors is that their voltage output is very frequency dependent. Given that the system is supposed to work from 5MPH to 150MPH there will be a very large variation in the signal amplitude at these two extremes - small at low speeds, very large (as in hundreds of volts) at high speed. I'll try and set it up in a bench drill to measure/demonstrate tomorrow.
But the point is the system will be setup to work reliably from 5mph to 150mph with standard clearances. If you move the sensor too close, it may overload the system at higher speeds - I know this is an issue with the Lotus Carlton ignition sensor, which is also a variable reluctance sensor. If the gap is too small, the ignition module misfires at high RPM due to being overloaded. The cure is to put in shims to space the sensor away from the timing wheel - there is a field service note in the dealer manual to do with this. It's unlikely to cause damage inside the control unit, but it can cause mis-triggers. The LC timing sensor spacing is specced at 1.5mm gap. The ABS sensors are similar, and 0.2-0.3mm clearance doesn't sound right to me.
Thanks, that is very useful information, and good to keep in mind since with new properly working sensors I'll probably have to increase the distance again. I have a 1mm thick rubber cloth that should result in a distance of 1.2-1.3 mm, which seems to be within reasonable span.
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EPC says that Omega A, Senator B & Omega B/B2 all use the same front hub assembly, GM# 90486467 / Opel KAT# 16-03-194. Not carried forward onto newer GM models.
And you're right, it's very likely that there is only one source supplying the hub assemblies and they are rebranded with whatever the buyer requests. It's also very likely that actual production ceased years ago and that anything available of whatever brand is actually old stock, dumped on the market to the highest bidder or bought up by old stock specialists. There are simply not enough Omegas or Cateras left to make it worthwhile for anyone to tool-up and manufacture any new parts.
The Ridex parts you ordered and the ESEN-SKV parts you received should be equivalent to each other and the factory fit and should work.
How did you clean out the bores for the sensors?
The bores for the sensors were sanded using a rotary multi tool.
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EPC says that Omega A, Senator B & Omega B/B2 all use the same front hub assembly, GM# 90486467 / Opel KAT# 16-03-194. Not carried forward onto newer GM models.
And you're right, it's very likely that there is only one source supplying the hub assemblies and they are rebranded with whatever the buyer requests. It's also very likely that actual production ceased years ago and that anything available of whatever brand is actually old stock, dumped on the market to the highest bidder or bought up by old stock specialists. There are simply not enough Omegas or Cateras left to make it worthwhile for anyone to tool-up and manufacture any new parts.
The Ridex parts you ordered and the ESEN-SKV parts you received should be equivalent to each other and the factory fit and should work.
How did you clean out the bores for the sensors?
The bores for the sensors were sanded using a rotary multi tool.
In which case Dave's suggestion will be the most cost effective solution.
Although I strongly suspect that you're going to try and fudge your current set up and at best, it won't work correctly and at worst could kill someone.
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If you haven't wasted money for an alignment yet , 8)
you have a great opportunity to save yourself lots of time and the cost of a second or third alignment (you'll need at least one )
put the original suspension back on, get some used/working knuckles with the genuine factory sensors fitted .get an alignment
bin the coil over tat you fitted :y
Omega/ Carerra is NOT a race car, drift machine , low-rider
original suspension works well for a comfortable family car ,which the Omega is ;)
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If you haven't wasted money for an alignment yet , 8)
you have a great opportunity to save yourself lots of time and the cost of a second or third alignment (you'll need at least one )
put the original suspension back on, get some used/working knuckles with the genuine factory sensors fitted .get an alignment
bin the coil over tat you fitted :y
Omega/ Carerra is NOT a race car, drift machine , low-rider
original suspension works well for a comfortable family car ,which the Omega is ;)
I'm lucky enough to have a friend who has access to a wheel alignment machine, so I can do it for free, and set it up however I want :y
I've found original used knuckles for sale, but I'm thinking about whether they really need replacing or not. I might end up buying them, too.
I deeply regret buying the coilover-kit. I'm not trying to make it a racing car, or anything extreme. I just needed to replace some suspension part since it failed the equivalent to MOT here, and the whole thing derailed. My suspension was very worn on the whole, so I took the decision to replace it all. And while doing so, I loved the idea of having adjustable ride height. I just wanted the car to sit slightly lower, for the looks, and since I like a slightly stiffer ride. I learnt afterwards that the camber is not even adjustable in the rear, and I'm now contemplating whether I can modify the rear suspension somehow, in order to adjust camber. It's gone too far, lol.
I really do not want to throw away the new coilover-kit. Also, everything is installed and ready to be aligned. It took very long.
I do not have the ride height set very low, and if I find the camber angle to be very far off I will either raise the height or try to find a way to adjust the camber.
I'm deep in the shit! If I had the opportunity to redo my original decision, I would choose to replace everything with new OEM parts. I don't want that now, because of all the time and money spent. Besides, it looks great being slightly lower than stock.
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I've found original used knuckles for sale, but I'm thinking about whether they really need replacing or not. I might end up buying them, too.
original used knuckles may well come with original ,working sensors (which is why i suggested it ) ;)
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Didn't get as far as I'd hoped today - took ages to find the old bits, and they needed quite a lot of cleaning. However, results so far...
https://ibb.co/Lkz0pzF
The Hubs are made by KOYO - both the bearings and the cast wheel flange are marked as such.
The ABS reluctor ring has 48 teeth, with an inner diameter of (about) 75mm and an outer diameter of 95mm. Each tooth is 2.5mm wide, and 2.5mm deep.
https://ibb.co/JdBJ3KT
The ABS sensors carry several markings on the wiring side, but these just look like date codes to me. I'll put it under the microscope at work (tomorrow) to see if I can get anything off it.
The sensor tip side looks like this...
https://ibb.co/VvTLPn7
The 'blade' of the sensor is 2mm wide, and 9mm long. It stands 5mm proud of the steering knuckle. The blade is aligned to point towards the hub axle axis. The body/barrel of the sensor is (about) 17mm diameter, and stands about 1.5mm proud of the steering knuckle.
The next step is to assemble the bearing onto the steering knuckle and measure the clearance from the tip of the sensor to the reuctor ring. Unfortunatley I can't do that at home - the surface rust on the knuckle doesn't let the bearing slide on, and I don't have the tools here to 'force it on'. So tomorrow I'll polish up the knuckle/bearing surface and measure it, and then take some 'scope readings of the signal generated by the sensor at various RPM's.
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Eibach springs drop the car about 30mm from stock.
Alignment numbers are well documented here, but most you can hope for with the rear end adjustment is that the thrust angle is zero and the side to side measurement is even. This is because it has one adjuster that affects both toe and camber.
The Omega isn't a car to try and 'stance'.
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Buying second hand ,genuine knuckles with genuine ABS sensors would be a way back to working ABS
not cheap though as you'd have to fit them, then get an alignment :(
what happened to the original sensors ???
I purchased low mile Omega B2 hubs/sensors as spares when i had omega As (Vauxhall Carltons) years ago :)
Yep! New sensors will be ordered. But I think I use the old knuckles, and use some material inbetween to increase the distance if needed.
I don't mind the fitting, as I do all the work on my car myself in my garage. Since I've replaced suspension I'll need an alignment regardless. So that's OK!
The original sensors broke as I tried removing them, while replacing suspension parts. The Haynes book stated to do so, but it would not have been necessary. All of the problems I have with the ABS is just an unlucky side effect from wanting to replace suspension parts.
If you do buy second hand knuckles, think long and hard before you attempt to remove the sensors from them. I have never, repeat NEVER, in about 10 attempts, managed to get one out in one piece. They are always 'welded' in. I suspect its dissimilar metal corrosion - the hub is cast iron, and the shell of the sensor is aluminium. Once water (and salt in the UK) get at it you're stuffed - the things will not come out in one piece if they've been in more than 5 minuites.
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I've found original used knuckles for sale, but I'm thinking about whether they really need replacing or not. I might end up buying them, too.
original used knuckles may well come with original ,working sensors (which is why i suggested it ) ;)
That's a great idea. The supply seems to be extremely small, but I did find this LH steering knuckle that has a sensor attached in the image: https://www.ebay.de/itm/352179150061?hash=item51ff835ced:g:pPAAAOSw5UFb~AJX&amdata=enc%3AAQAIAAAAwM7GscXU4moyE%2FNtdssglV6fk9Kp3BdaO%2BEqOFW0w%2BN8NEnj0ZIGYd6NCsycmjacQh8LEh1v%2BIZoKU7zRJMZ%2F7UPD46a3SmxXw82zbrNGPv%2BplHHB3by4GFu%2BxDrgnbv6LmQ%2BzRmwMYfRuOSVZJUqOvi4TuNNC4Wi3pGN5S%2BWtGsAN%2FiYfdUsADoGZccywjXcUBaKZ7H7mmGJWFBhr0pYpTdwKJgWgqRgukCUQY3p%2FLbz5owuEax3wMcwLnp7qWbMg%3D%3D%7Ctkp%3ABk9SR9CNvc7vYg (https://www.ebay.de/itm/352179150061?hash=item51ff835ced:g:pPAAAOSw5UFb~AJX&amdata=enc%3AAQAIAAAAwM7GscXU4moyE%2FNtdssglV6fk9Kp3BdaO%2BEqOFW0w%2BN8NEnj0ZIGYd6NCsycmjacQh8LEh1v%2BIZoKU7zRJMZ%2F7UPD46a3SmxXw82zbrNGPv%2BplHHB3by4GFu%2BxDrgnbv6LmQ%2BzRmwMYfRuOSVZJUqOvi4TuNNC4Wi3pGN5S%2BWtGsAN%2FiYfdUsADoGZccywjXcUBaKZ7H7mmGJWFBhr0pYpTdwKJgWgqRgukCUQY3p%2FLbz5owuEax3wMcwLnp7qWbMg%3D%3D%7Ctkp%3ABk9SR9CNvc7vYg)
I could solder it to the wiring of one of my old broken sensors. I guess there is no guarantee the sensor will still be there on the steering knuckle when it arrives, though. Also, there is no guarantee it'll work, ofcourse. The tip of the sensor looks really roughed up.
The same seller also has a RH steering knuckle, without sensor on the image.
The most attractive option from my perspective is to order two new sensors, and install them on my current steering knuckles.
Is there a general agreement on here that it would be a good idea to install new steering knuckles?
If I were convinced that I need new steering knuckles, I'd order both these steering knuckles along with only one new sensor, and give it a try getting the used sensor on the LH steering knuckle to work. But I'm not fond of the idea of finding out the sensor won't work, and having to wait for another separate order to arrive. Nor can I get away from the fact that the bore for the sensor on the used steering knuckles will need sanding, too. A lot of extra work awaits, with the ordering of steering knuckles.
I'm running short of time since I need this car on the road asap to get to work when winter gets here. Preferably several weeks ago. Of course, I do not intend to compromise on safety. Everything will be properly tested.
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Buying second hand ,genuine knuckles with genuine ABS sensors would be a way back to working ABS
not cheap though as you'd have to fit them, then get an alignment :(
what happened to the original sensors ???
I purchased low mile Omega B2 hubs/sensors as spares when i had omega As (Vauxhall Carltons) years ago :)
Yep! New sensors will be ordered. But I think I use the old knuckles, and use some material inbetween to increase the distance if needed.
I don't mind the fitting, as I do all the work on my car myself in my garage. Since I've replaced suspension I'll need an alignment regardless. So that's OK!
The original sensors broke as I tried removing them, while replacing suspension parts. The Haynes book stated to do so, but it would not have been necessary. All of the problems I have with the ABS is just an unlucky side effect from wanting to replace suspension parts.
If you do buy second hand knuckles, think long and hard before you attempt to remove the sensors from them. I have never, repeat NEVER, in about 10 attempts, managed to get one out in one piece. They are always 'welded' in. I suspect its dissimilar metal corrosion - the hub is cast iron, and the shell of the sensor is aluminium. Once water (and salt in the UK) get at it you're stuffed - the things will not come out in one piece if they've been in more than 5 minuites.
Haha, don't worry. I've learnt my lesson, and will never again attempt to remove wheel speed sensors unless I intend to replace them.
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Didn't get as far as I'd hoped today - took ages to find the old bits, and they needed quite a lot of cleaning. However, results so far...
https://ibb.co/Lkz0pzF
The Hubs are made by KOYO - both the bearings and the cast wheel flange are marked as such.
The ABS reluctor ring has 48 teeth, with an inner diameter of (about) 75mm and an outer diameter of 95mm. Each tooth is 2.5mm wide, and 2.5mm deep.
https://ibb.co/JdBJ3KT
The ABS sensors carry several markings on the wiring side, but these just look like date codes to me. I'll put it under the microscope at work (tomorrow) to see if I can get anything off it.
The sensor tip side looks like this...
https://ibb.co/VvTLPn7
The 'blade' of the sensor is 2mm wide, and 9mm long. It stands 5mm proud of the steering knuckle. The blade is aligned to point towards the hub axle axis. The body/barrel of the sensor is (about) 17mm diameter, and stands about 1.5mm proud of the steering knuckle.
The next step is to assemble the bearing onto the steering knuckle and measure the clearance from the tip of the sensor to the reuctor ring. Unfortunatley I can't do that at home - the surface rust on the knuckle doesn't let the bearing slide on, and I don't have the tools here to 'force it on'. So tomorrow I'll polish up the knuckle/bearing surface and measure it, and then take some 'scope readings of the signal generated by the sensor at various RPM's.
Thank you so much for taking your time to look all that up!
The sensor looks different from the one installed on Omega B.
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For the earlier Carlton/Senators, it looks like the 'current' part numbers are...
VX-90510208, OP-5-30-409, BOSCH 0265001220.
Given that the hubs and knuckles are the same on Omega B, I suspect these will fit and work just fine. Might be worth a google to see if you can get these.
Interestingly, on Rock Auto the seem to list 4 or 5 aftermarket sensors for the 2001 Cadilac Catera. The pictures show these as having plastic bodies. I wonder if these are less prone to "rusting in"
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Was that a genuine question?
You've potentially modified your current hubs to the point that even a genuine sensor won't fit correctly and you need replacement sensors.
It's the quickest cost effective solution to resolve your original issue.
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And....just been looking at your oscilloscope shots.
The frequency readout say 116Hz, 77Hz and 91Hz. There are 48 teeth on the reluctor ring, so the actual wheel speeds will be one forty eighth of this - 2.41Hz (145 RPM), 1.60Hz (96 RPM) and 1.90Hz (114 RPM)
Do you really mean you were testing at 2 RPM - or two revs per second (i.e. 2Hz = 120 RPM)?
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right side clicky (https://www.ebay.co.uk/itm/115516871504)
left side clicky (https://www.ebay.co.uk/itm/125499279846)
not sure what postage to USA would be though :-\
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And....just been looking at your oscilloscope shots.
The frequency readout say 116Hz, 77Hz and 91Hz. There are 48 teeth on the reluctor ring, so the actual wheel speeds will be one forty eighth of this - 2.41Hz (145 RPM), 1.60Hz (96 RPM) and 1.90Hz (114 RPM)
Do you really mean you were testing at 2 RPM - or two revs per second (i.e. 2Hz = 120 RPM)?
Should be revs per second, ofcourse! My bad.
The frequency I'm referring to is for the signal, i.e. the passing of teeth. 96 Hz = 120 RPM (or 2 rev/s)
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Was that a genuine question?
You've potentially modified your current hubs to the point that even a genuine sensor won't fit correctly and you need replacement sensors.
It's the quickest cost effective solution to resolve your original issue.
I actually don't believe my current steering knuckles will pose a problem with genuine sensors.
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right side clicky (https://www.ebay.co.uk/itm/115516871504)
left side clicky (https://www.ebay.co.uk/itm/125499279846)
not sure what postage to USA would be though :-\
Thanks for the links. I noticed that the sensors do not have the GM-label on them, as the sensor in my link has.
Could it be that they come from factory both with and without the label, perhaps depending on production date or something else? Or could there be a risk that the sensors are not genuine?
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They came from a working car, just fit them as they are.
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I have ordered the two steering knuckles that Dave suggested. Thank you! They'll arrive in 2-3 weeks.
Fingers crossed!
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right side clicky (https://www.ebay.co.uk/itm/115516871504)
left side clicky (https://www.ebay.co.uk/itm/125499279846)
not sure what postage to USA would be though :-\
Thanks for the links. I noticed that the sensors do not have the GM-label on them, as the sensor in my link has.
Could it be that they come from factory both with and without the label, perhaps depending on production date or something else? Or could there be a risk that the sensors are not genuine?
It's Ebay, if the parts don't work, claim a refund ;)
though I've rarely had problems buying from ebay ,others may disagree
I've TRIED to find you a cost effective way out of the hole you've dug
just fit them, reset the fault codes, get your alignment and inspection and drive it :)
sincerely the best of luck moving forwards with your project :y
Oh , and book lots of chiropractor appointments for when your back is aching after fitting coilovers :P
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right side clicky (https://www.ebay.co.uk/itm/115516871504)
left side clicky (https://www.ebay.co.uk/itm/125499279846)
not sure what postage to USA would be though :-\
Thanks for the links. I noticed that the sensors do not have the GM-label on them, as the sensor in my link has.
Could it be that they come from factory both with and without the label, perhaps depending on production date or something else? Or could there be a risk that the sensors are not genuine?
It's Ebay, if the parts don't work, claim a refund ;)
though I've rarely had problems buying from ebay ,others may disagree
I've TRIED to find you a cost effective way out of the hole you've dug
just fit them, reset the fault codes, get your alignment and inspection and drive it :)
sincerely the best of luck moving forwards with your project :y
Oh , and book lots of chiropractor appointments for when your back is aching after fitting coilovers :P
Your suggestion to buy steering knuckles complete with used sensors was brilliant :) In addition to being cost effective, it eliminates the risk of something being wrong with my steering knuckles.
Haha, I might need some recovery after this all is over. Physically as well as mentally :D
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Todays results from the Somerset 'elf-n-safety' conscious test labs....
The Markings on the sensor are 0265 001 220, which is the Bosch part number. The word Bosch is also molded into the rubber boot on the sensor.
I polished up the knuckle, and mounted the hub. Not torqued up to 300Nm, but tight enough for this. Then mounted it in the bench mill, with a bodged up drive assembly, and got it as centered as I could.
(https://i.ibb.co/LtR9Kwf/IMG-9726.jpg)
Then fired up the feeler gauges to measure the clearance...
(https://i.ibb.co/q1vdZR3/IMG-9728.jpg)
The 0.8mm gauge goes in fine, the 0.9mm is snug, and the 1.0mm will not go in. So I'd say the installed clearance from sensor tip to reluctor ring is +/- 0.9mm (ish). I wouldn't argue or be worried about any value in the 0.8mm-1.0mm range though.
Then fire up the bench mill, and record the sensor waveforms on a cheap USB scope. The setup wasn't very well balanced, so I lost my bottle at 700Hz as the thing was shaking the desk and threatening to tip my cup of coffee over. Anyway...Scope traces at 100Hz, 200Hz, 400Hz and 700Hz.
(https://i.ibb.co/ZLPSdCP/100HZ.jpg)
(https://i.ibb.co/VB147fH/200HZ.jpg)
(https://i.ibb.co/TM4Zrdg/400HZ.jpg)
(https://i.ibb.co/8BSzQBy/700HZ.jpg)
Assuming standard tyres (235R45-17) with a rolling radius of 79.57 inches (2021mm), then these sensor frequencies equate to...
100Hz = 2.08 Rev/s = 165.5 inches/sec = 9.4 MPH
200Hz = 4.17 Rev/s = 331.0 inches/sec = 18.8 MPH
400Hz = 8.33 Rev/s = 662.0 inches/sec = 37.6 MPH
700Hz = 14.16 Rev/s = 1158.5 inches/sec = 65.8 MPH
As you can see, the sensor signal grows from about 140mV ptp at 100Hz (9.4MPH) to 630mV ptp at 700Hz (65 MPH). I'll leave you to extrapolate what happens at other speeds. The point is the output from the sensor is probably supposed to be of the order 100mV ptp at 5MPH, up to perhaps 1V ptp at 100MPH.
There will be quite a large tolerance in the ABS system to cope with mechanical and sensor variations - but these are the figures I can demonstrate.
Remember this is all Carlton gear. There is a possibility the Omega B is different. However, your "Holstein" sensors are producing significantly less signal voltage than these Bosch ones do (even at your reduced clearance), and I strongly suspect they are the cause of your issues.
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Once you get the bit between your teeth, Malcolm......... ;D ;D
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Not to mention that the signal from the Carlton seems to be less noisy than the OP is getting.
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Once you get the bit between your teeth, Malcolm......... ;D ;D
The question occasionally crops up in 'another place', and now I've got something to beat the non-believers over the head with ;D
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Thank you for your input and measurements, LC0112G!
It's so nice to have a benchmark, and to have ones suspicions confirmed. Your signal is significantly stronger.
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This will be the final update, an end to it all.
The steering knuckles arrived, and were installed tonight. Look below for the result!
(https://i.ibb.co/TgDwt7t/IMG-20231108-194714.jpg) (https://ibb.co/sVpgqNq)
(https://i.ibb.co/JFsdM3f/IMG-20231108-194739.jpg) (https://ibb.co/x87sRFp)
(https://i.ibb.co/vPpVYyS/Measurement-Good-Sensor.png) (https://ibb.co/7WPj4Mq)
1.220 V @ 76 Hz (~1.6 revolutions / sec). For comparisson, I previously managed to get about 30mV at that speed with the other sensors.
I'm a bit surprised, the voltage is even higher than I was hoping for. Regardless, the signal is super clean and the ABS is working flawlessly. Case closed. FINALLY!
Conclusion: Avoid shady beer-named brands for sensors. And do not expect to be able to remove ABS-sensors.
Thank you all for helping me out!