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Author Topic: Help! Error code P1700  (Read 5651 times)

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JamesV6CDX

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Re: Help! Error code P1700
« Reply #45 on: 11 May 2022, 18:47:08 »

Hi Everyone,

Just got back - good to meet you Nick!

Having had a good look over this car today, I wanted to share our findings (and lack of findings) in relation to this, and see if people agree with my line of thinking, or have any other suggestions, based on this update, on where we go next.

The symptoms / complaint have already been described on this thread, so I won't repeat that.

So, first job, was to finish over changing the selector switch. After partially removing the heatshields, I was able to get to the electrical connector for the selector switch, and change it over. The replacement certainly looked clean, and okay.

After installing the switch, I started up the car, and made sure it's aligned correctly. I am sure it is - I say this because the car only starts in P or N, and the relevant lights illuminate next to each gear - without the "multi light" display that's usually attributable to a buggered selector switch.

I noticed the engine light was on (the spanner symbol), so using "Scan My Opel", read the fault codes.

They were:

P1625-02: Internal Power Control Final Stage Low Input.

P0748 -06: Unknown Error

I stopped the engine, and put the ignition switch to "on" but not started (so the dash lights up). I then cleared the codes. The codes momentarily cleared, but, then came straight - and the warning light was back on within seconds. It was the exact same two codes, which returned.

I double checked the selector switch fitment / connections, which were okay, and tried aqain. Codes kept returning.

Given these same codes were also present prior to me arriving, and with the old selector switch fitted - I think we can safely say that sadly this isn't a selector switch problem, but something more complex than first thought. The same codes are returning, regardless of which switch is fitted.

At this point, I decided to check the electricals as thoroughly as one can, given today's rain! I dis-assembled, checked, and re-seated the three large round loom plugs near the battery tray. I also removed, checked, and cleaned the earths. In addition, I visually checked, and removed / reseated the round loom connector, which plugs into the passenger side of the autobox.

What I think is noteworthy, is that the fault codes are persistent, in that they come back immediately after being cleared, even without the engine being started. This, to me, is indicative of an electrical, rather than a mechanical fault. But, I am starting to think the fault is with the electrics inside the box itself, not within the loom / ECU, which is all in good visual condition.

I also tried my code reader - this only came up with one of the codes - the P1625, however, mine described the fault as "TCM Flash Checksum Fault (Saturn)".

I don't for a minute think the gearbox ECU is faulty - I have never, ever seen any ECU fail on an Omega (aside of the ABS ones), and I think the code is more likely a result of something else. I don't subscribe to "the fault code says it's xyz, because we all know the codes can arise from some other input error, somewhere else. But - for completeness, I tried a known good ECU that Nick had spare. Same part number. I installed this, cleared out the codes, and - you guessed it - the same two came back. So, I think on this basis, we can preclude any form of gearbox
ECU problem.
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JamesV6CDX

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Re: Help! Error code P1700
« Reply #46 on: 11 May 2022, 18:48:13 »



On a road test - the car is stuck in top gear (as per full limp mode), but will drive manually through the gears. However - the manual changes are rough - going slowly from 1st to second results in a noticable "thump". This was reminiscent of thrust washer failure symptoms, if anyone remembers sassanach's insightful posts around this. I would have liked to have dropped the sump to confirm if any remains are present, however, the rain at this point was torrential and it wasn't feasible today.

The factors leaning away from thrust washer, are, they rarely fail on unmodified 2.5 / 2.6 engines with AR25 boxes, in my experience (although not impossible). And also, the car was reported to have been driving fine, until the light suddenly appeared from nowhere after a restart.

We can preclude low fluid level or poor fluid - as, the fault code returns even with the engine off (when there is no pressure / ATF being pumped) and therefore the solenoids are not operating.

As an aside - I always subscribe to the "fix any known issues first". When told the car had a recent battery blip, I fitted / tried Nick's new battery, but this made no odds.

In live data, the battery voltage (given by both the gearbox ECU and engine ECU) is over 14v (14.7 IIRC). It did cross my mind "is this too high", and made me wonder if an over-zealous alternator might be playing a part. The alternator looked new, and pattern - although it has been on the car for at least a couple of years, I believe, without there ever being an issue. And also, I am not sure how a too high voltage would result in numerous "low power" codes. Additionally, the alternator doesn't give power when the engine isn't running, and the fault returns in that environment - so thinking about it I don't think the alternator / over volts is a contender.

When doing a bit of research into the fault code, the Scan My Opel App describes it as:

"Final stage diagnosis in control unit. Short to ground in circuit to control unit terminal 52, 5

Above Condition must be fulfilled for at least 0.02s. Effect - Emergency mode is activated, The malfunction indication is switched on. Concerned Terminals, 52, 5. If anyone has a wiring diagram, and can shed any insight on this, it's likely to be beneficial.

I am personally leaning towards a failure inside the box, but, I don't want to condemn it without sleeping on it and thinking it through a bit more - and bouncing ideas around on here. I find it interesting that at around 70k, the box had solenoids and new ATF - can you recall nick, what prompted this work, was there a symptom/fault or something not right?

We would both be very grateful for any opinions. We are going to fix this OOF style - even if it does ultimately need a second hand 'box. The only difference being, it would probably take me a day now (with lifting help) not four hours like when I was back in my prime :D
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JamesV6CDX

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Re: Help! Error code P1700
« Reply #47 on: 11 May 2022, 18:50:26 »

This Omega is a lovely example, free of the usual arch-rot, I would really like to get it back to it's old-self :y
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Migalot

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Re: Help! Error code P1700
« Reply #48 on: 11 May 2022, 19:03:48 »

I find it interesting that at around 70k, the box had solenoids and new ATF - can you recall nick, what prompted this work, was there a symptom/fault or something not right?

Thanks again, James. Great to meet you!

The 2/3 solenoid was replaced as, intermittently, the car would kick like donkey going from 2 to 3 and the spanner light would come on. I was able to overcome this by turning the ignition off and restarting, after which the spanner light would go out.

Cured once the new solenoid was installed (and refilled with new Dexron and filter)

Nick
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JamesV6CDX

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Re: Help! Error code P1700
« Reply #49 on: 11 May 2022, 19:13:49 »

I find it interesting that at around 70k, the box had solenoids and new ATF - can you recall nick, what prompted this work, was there a symptom/fault or something not right?

Thanks again, James. Great to meet you!

The 2/3 solenoid was replaced as, intermittently, the car would kick like donkey going from 2 to 3 and the spanner light would come on. I was able to overcome this by turning the ignition off and restarting, after which the spanner light would go out.

Cured once the new solenoid was installed (and refilled with new Dexron and filter)

Nick

Ta - I'm sure you did say, just my memory!

Be positive - OOF is a great resource, and we WILL sort this :y
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Doctor Gollum

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Re: Help! Error code P1700
« Reply #50 on: 11 May 2022, 19:15:45 »

Fluid level/condition is about the last gearbox check.

Beyond that, cam sensor, on a hunch... (it causes similar apparent symptoms with the 2.2)

https://www.ebay.co.uk/itm/301655465678 I know this one is used, but it should be more reliable than a cheapy aftermarket one for testing purposes  ;)

Takes about 30 seconds to swap out  :y
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JamesV6CDX

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Re: Help! Error code P1700
« Reply #51 on: 11 May 2022, 19:25:31 »

Thanks DG,

Engine revs freely and no cam sensor codes. I'd be surprised, as they are very robust on these. I wouldn't have thought if it were the cam sensor, it would cause (low voltage / short) codes to appear, though, when the engine isn't even running? Being a hall-effect sensor, the cam sensor won't even give any input, with just the ignition on? :y
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Doctor Gollum

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Re: Help! Error code P1700
« Reply #52 on: 12 May 2022, 02:10:38 »

On the 2.2 it gives the dreaded P1700 (replace gearbox) code along with the light, V6 should give a cam sensor code but in the absence of anything obvious wrong with the gearbox... :-\

That said, any evidence of moisture/wiring damage around the gearbox ecu (right hand kick panel)?
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grifter

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Re: Help! Error code P1700
« Reply #53 on: 12 May 2022, 06:02:11 »

Haven't had a wee mouse in there nibbling some of the wires? I always wonder if that is likely the cause with these strange problems.
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JamesV6CDX

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Re: Help! Error code P1700
« Reply #54 on: 12 May 2022, 12:09:31 »

On the 2.2 it gives the dreaded P1700 (replace gearbox) code along with the light, V6 should give a cam sensor code but in the absence of anything obvious wrong with the gearbox... :-\

That said, any evidence of moisture/wiring damage around the gearbox ecu (right hand kick panel)?

None at all. Wiring and ECU area bone dry and it all looks as new up there.

I agree a cam sensor can throw a 1700. But 1700 is just a generic engine ECU code to tell us that the transmission ECU has also logged DTC(s). The P1625 (low power) code, I am convinced, wouldn’t arise from a faulty hall sensor.

I’d love to be proven wrong, but I just can’t see it being that :(

For elimination purposes we can study the wiring diagrams and see if we can do some continuity testing between the relevant ECU pins and gearbox multiplug. But I’m still leaning towards the box being shagged. Especially given the nasty thump on changing :y

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Migalot

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Re: Help! Error code P1700
« Reply #55 on: 12 May 2022, 15:57:55 »

I've taken a punt and ordered a cam sensor. With a bit of luck it will be here tomorrow, though I may have missed the next-day delivery deadline by a few minutes.

It's worth a go and the cost is minimal in comparison to a replacement gearbox.

I do wish these electrical faults were simpler to rectify.
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Migalot

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Re: Help! Error code P1700
« Reply #56 on: 12 May 2022, 17:02:55 »

As it's quiet in my road this afternoon I went back out to the car, started it and just let it tick over. it's definitely running rougher than before this fault showed up. The tacho is not as rock solid as before either – no large up and down variation, but definitely not what it used to be. Also, I smelled a bit of unburnt fuel from the exhaust yesterday.

I came across this online just now:
Because the camshaft is such a critical part of the engine, a failing sensor can throw out a myriad of symptoms at you.
Here are some of the most common ones:

[Includes]

Limp mode – The vehicle starts and goes but you just can’t accelerate past 30-40 mph. The engine is able to operate and get you back home, but enters a “limp mode” – an emergency override, which limits power and engine speed to prevent damage to the mechanical components


https://autoquarterly.com/diagnosing-and-repairing-a-bad-camshaft-position-sensor/

I'm holding out for a simple solution...but I may just be deluding myself. ;D

 
« Last Edit: 12 May 2022, 17:12:42 by Migalot »
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dave the builder

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Re: Help! Error code P1700
« Reply #57 on: 12 May 2022, 19:11:10 »

Most Vauxhall petrol cars over fuel on start up and stink of petrol ,perfectly normal
I hope the cam sensor is a fix for your issues though  :)
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JamesV6CDX

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Re: Help! Error code P1700
« Reply #58 on: 12 May 2022, 19:37:53 »

Most Vauxhall petrol cars over fuel on start up and stink of petrol ,perfectly normal
I hope the cam sensor is a fix for your issues though  :)

I agree it was running slightly lumpy (although not misfiring).

I genuinely - really - want to be proven wrong, but I can’t see the cam or crank sensor (or any other minor engine imperfection) causing this TCM code :(
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Re: Help! Error code P1700
« Reply #59 on: 12 May 2022, 19:40:33 »

Mechanical wear and electrical gremlins are different issues. The gearbox isn't that bright ;)
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