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Maintenance Guides / Omega speedometer not working; ABS/ TC lights on.
« on: 12 July 2006, 19:43:27 »
Omega MY98 onwards ABS/ TC lights on; speedometer not working
The first thing to try in this situation is to check and clean the ABS sensors on each wheel (especially the N/S/R which is where the speedo feed comes from)
If after doing this the lights are still on and the speedo isn't working then ideally find someone with a tech2 or similar system and see if the computer can communicate with the ABS ECU attached to the hydraulic modulator.
If it can't communicate with the ECU then the problem almost certainly lies with the ABS ECU itself. Unfortunately a very common problem, especially on MY98> versions (VIN W1000001 onwards)
Vauxhall charge about £800 to do the job all in with the unit itself costing about £300.
It is not a nice job to fit and requires patience amongst other things.
To access the unit you need to remove: (based on a 1998 3.0 MV6)
-Battery
-Engine relay/ ECU box
-Top radiator hose
-Coolant transfer pipe (thermostat feed pipe) (for clearance)
-Top plenum (optional but easier to locate the transfer pipe properly with it off)
-PAS pipe from top of pump for clearance
-PAS reservoir (ideally but can be moved out of the way, but will stretch pipes.)
-Undo all engine wiring loom round connectors from rear edge of battery tray.
When you are removing the PAS components note that the reservoir is directly above the ABS module, so make sure the fluid doesn't pour on the unit when you remove it.
The main top electrical plug on the ABS ECU has a sliding retaining clip. This slides towards the outside of the car, and is quite fiddly to get to even with all the bits out. You need to slide it as far as it will possibly go to allow the plug to come off.
Underneath the module is another, small, plug which has a more conventional plastic clip. Remove this and make sure the wire doesn't disappear into the bowels of the engine bay.
The ECU is held to the modulator with six small torx screws. The screws are well set back and in small apertures as can be seen from the picture below so you will need torx bits at least 2" long to actually reach the bolts. Also bear in mind with the unit on the car you can only actually see the top two screws. The rest are all done by touch, and a lot of luck.
To undo the bolts I used an angled screwdriver bit holder as there is extremely limited access to the bolts. See the following link:
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331405&ts=46440&id=61688
Once all the screws are undone (You may lose a couple but the new unit should come with new screws) the unit should just come straight off. Be careful not to get any dirt or fluid on the exposed section of the ABS modulator, and give the surface where the module meets it a gentle clean.
Refitting is ther reversal of removal to quote Haynes, but fitting the screws is much more difficult than removing them. Gently fit the top two to hold the unit in place. What I did next was to use insulating tape to stick the screw heads to the torx bit then very gently try and locate them. This will take many tries and a lot of swearing. The advantage of insulating tape is that when the screws are tight the tape will slip off of the bolt.
Once all six bolts are in place reconnect the plugs, refit the coolant transfer hose (replace the two rubber O rings), refit the plenum if removed (replace the manifold to plenum seals).
From then on refit as normal, and when it is all back together with a little bit of luck the lights should go off and the speedo should work again.
This is not a job I would wish on to anyone, but my point here is that it is possible to do it as a DIY job, even if it is a pain in the arse, and you will save yourself £400 - 500 worth of labour.
Any questions feel free to mail me.
The first thing to try in this situation is to check and clean the ABS sensors on each wheel (especially the N/S/R which is where the speedo feed comes from)
If after doing this the lights are still on and the speedo isn't working then ideally find someone with a tech2 or similar system and see if the computer can communicate with the ABS ECU attached to the hydraulic modulator.
If it can't communicate with the ECU then the problem almost certainly lies with the ABS ECU itself. Unfortunately a very common problem, especially on MY98> versions (VIN W1000001 onwards)
Vauxhall charge about £800 to do the job all in with the unit itself costing about £300.
It is not a nice job to fit and requires patience amongst other things.
To access the unit you need to remove: (based on a 1998 3.0 MV6)
-Battery
-Engine relay/ ECU box
-Top radiator hose
-Coolant transfer pipe (thermostat feed pipe) (for clearance)
-Top plenum (optional but easier to locate the transfer pipe properly with it off)
-PAS pipe from top of pump for clearance
-PAS reservoir (ideally but can be moved out of the way, but will stretch pipes.)
-Undo all engine wiring loom round connectors from rear edge of battery tray.
When you are removing the PAS components note that the reservoir is directly above the ABS module, so make sure the fluid doesn't pour on the unit when you remove it.
The main top electrical plug on the ABS ECU has a sliding retaining clip. This slides towards the outside of the car, and is quite fiddly to get to even with all the bits out. You need to slide it as far as it will possibly go to allow the plug to come off.
Underneath the module is another, small, plug which has a more conventional plastic clip. Remove this and make sure the wire doesn't disappear into the bowels of the engine bay.
The ECU is held to the modulator with six small torx screws. The screws are well set back and in small apertures as can be seen from the picture below so you will need torx bits at least 2" long to actually reach the bolts. Also bear in mind with the unit on the car you can only actually see the top two screws. The rest are all done by touch, and a lot of luck.
To undo the bolts I used an angled screwdriver bit holder as there is extremely limited access to the bolts. See the following link:
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=A331405&ts=46440&id=61688
Once all the screws are undone (You may lose a couple but the new unit should come with new screws) the unit should just come straight off. Be careful not to get any dirt or fluid on the exposed section of the ABS modulator, and give the surface where the module meets it a gentle clean.
Refitting is ther reversal of removal to quote Haynes, but fitting the screws is much more difficult than removing them. Gently fit the top two to hold the unit in place. What I did next was to use insulating tape to stick the screw heads to the torx bit then very gently try and locate them. This will take many tries and a lot of swearing. The advantage of insulating tape is that when the screws are tight the tape will slip off of the bolt.
Once all six bolts are in place reconnect the plugs, refit the coolant transfer hose (replace the two rubber O rings), refit the plenum if removed (replace the manifold to plenum seals).
From then on refit as normal, and when it is all back together with a little bit of luck the lights should go off and the speedo should work again.
This is not a job I would wish on to anyone, but my point here is that it is possible to do it as a DIY job, even if it is a pain in the arse, and you will save yourself £400 - 500 worth of labour.
Any questions feel free to mail me.
