Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
That's a COMS error being caused by another fault!! Is the clutch/XYZ sensor/calibration OK?
If not that error will keep reappearing!yµ (idµ - eAµ) ψ=mψ
22nd Feb 2021 12:28 am
GDM
Member Since: 18 Oct 2020
Location: Midhurst, West Sussex
Posts: 144
Right, so I recalibrated the transfer case with the IID tool and took the car for a run this evening. The yellow warning light stayed off until I went to change into second gear, then it came on and displayed the same error message in the screen.
The gear display is working in all gears except for reverse, although there is a delay in displaying the selected forward gear.
Again, when I came out of reverse the reversing lights and reversing sensors worked momentarily. I also discovered that if I deliberately hold the gear lever between reverse and neutral and keep it pushed towards the passenger's seat the lights will sometimes stay on.
I did try to locate the transfer case ECU to check for corrosion on the connector but I couldn't see it behind the battery. Is that definitely where it is located?
25th Feb 2021 8:48 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
So you still have a calibration issue, sometimes you need a few "takes" to get calibration right!
The one thing you might need to watch out for here is clutch slippage.
Watch the rev counter carefully as you accelerate hard up the gears. The rev counter should be progressive and consistent in it's path. If you see the slightest jump of the needle I'd be seriously concerned about your clutch
Clutch slip = calibration lost, but certainly do check the connections in the TCM. And yes, it's behind the battery. (There's plenty of pics on here if you do a quick search.) yµ (idµ - eAµ) ψ=mψ
25th Feb 2021 9:02 pm
GDM
Member Since: 18 Oct 2020
Location: Midhurst, West Sussex
Posts: 144
I guess I can try recalibrating again with the IID tool.
I haven't noticed the clutch slipping, even when towing 3500Kg and I would have thought that would have shown up any potential to do so.
I found an extract from a workshop manual on the internet and it looks like the ECU is directly behind the fuse-box. I will check the connections over the weekend.
25th Feb 2021 11:58 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
No, the Transfer Case Module (TCM or 4x4 module) is behind the battery. Let the car sleep, then remove the battery, then open the black cover and you will see the TCM in front of the ECM(engine) You might have water ingress but I doubt it, as your dash will light up like a Christmas tree if it did. Still, no harm to inspect the terminals and rule it out.
As for the clutch you can still have a slip problem without it being very noticeable!! The rev counter really is your friend here as any slight slippage will be identified by the needle momentarily jumping if it's on its way out.
The heavy dual mass flywheel and/or clutch can partially slip in the early stages of failure causing the transfer case calibration to be lost. This is not always obvious slippage as in other vehicles!
I replaced a clutch on a D3 recently for this very reason. On removal it actually looked brand new but had been there since it left the factory, and had done 150k. I was asked "did you really need to change that, it looks perfect"?
I said "you'll find the answer to that question when next he drove the car" (which he did )
You're problem may not be the clutch, but just be aware of it! Failed calibration also caused by air in clutch hydraulics, (I may have mentioned this earlier) a faulty XYZ switch, or poor connection/wiring fault to either the TCM or XYZ switch. yµ (idµ - eAµ) ψ=mψ
26th Feb 2021 1:24 am
GDM
Member Since: 18 Oct 2020
Location: Midhurst, West Sussex
Posts: 144
The diagram was referring to the fuse-box next to the battery.
I am wondering whether it might be the XY switch. It seems odd that the reverse lights do work when coming out of reverse and holding the lever towards the passenger's seat.
27th Feb 2021 1:43 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
I would have thought there would be a dtc to support an XYZ fault! Its an expensive switch and not easily found in a breakers as most are auto trans.
Worth a try perhaps?yµ (idµ - eAµ) ψ=mψ
27th Feb 2021 1:54 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
TCM is not in the fuse box. yµ (idµ - eAµ) ψ=mψ
27th Feb 2021 1:55 am
GDM
Member Since: 18 Oct 2020
Location: Midhurst, West Sussex
Posts: 144
Cleared all of the fault codes yesterday.
Took out the battery today and checked the connections on the TCM. A very slight bit of corrosion but nothing serious, so sprayed them with contact cleaner and reassembled.
I drove the car in first gear for a while, I was on and off the clutch but the light stayed out until I changed into second, then it came on immediately. Seems like it might be the XY sensor.
25th Apr 2021 11:46 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
Is the original C1A41 clutch pedal sensor fault resolved?
And did you clean the TCM terminals not just spray them?yµ (idµ - eAµ) ψ=mψ
26th Apr 2021 12:03 am
GDM
Member Since: 18 Oct 2020
Location: Midhurst, West Sussex
Posts: 144
I haven't had the clutch pedal sensor fault for some time now.
The TCM terminals weren't very bad at all. Spraying them with contact cleaner was really just a precautionary thing.
26th Apr 2021 10:50 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
OK but just be aware if there is any corrosion on the pins however slight it may appear, can very easily impede signals yµ (idµ - eAµ) ψ=mψ
26th Apr 2021 11:05 pm
GDM
Member Since: 18 Oct 2020
Location: Midhurst, West Sussex
Posts: 144
Hmm. Might be worth a clean then.
26th Apr 2021 11:42 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
If you have electric contact grease its great at preventing corrosion build up in the first place.
If not you can get away with petroleum jelly which will keep the contacts clean as well as eating any build-up on the contact surfaces. Press it into the female plug contacts, the male side will then be coated when you reassemble.
Be careful if you have to clean any pins they're easily broken if corroded.yµ (idµ - eAµ) ψ=mψ
26th Apr 2021 11:58 pm
GDM
Member Since: 18 Oct 2020
Location: Midhurst, West Sussex
Posts: 144
I can't believe that I have actually managed to get this sorted today and that it was so easy in the end.
I had tried the manual reset based on instructions from previous posts where it said you could do the procedure in low range if you didn't have a lot of space. I did it it in high range, as I was going to a fairly long stretch of road. It didn't work and neither did the IID tool reset.
This guy does it in low ratio, so, as Disco Mikey knows his stuff, I followed this video exactly.
Everything went to plan, it now displays gears instantly on the dash, the parking sensors and reversing lights are working, and so is the auto-release handbrake.
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I was asked "did you really need to change that, it looks perfect"?
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