Citroen C4 vtr+

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GiveMeABreak
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Re: Citroen C4 vtr+

Post by GiveMeABreak » 18 Oct 2019, 11:24

Ideally I would need the fault codes that were present at the time the vehicle was diagnosed, as I am working blind here 8-) - but I'm examining some of the CAN data connections now between the various ECUs and differing Data networks to see if I can see how each specifically interacts - to try and determine how the instrument displays are going into backup mode as a result of any ABS pump fault.

I'll post again when I've deciphered or got a brain drain :-D

Gramps1970
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Re: Citroen C4 vtr+

Post by Gramps1970 » 18 Oct 2019, 12:51

Thanks

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Re: Citroen C4 vtr+

Post by admiral51 » 18 Oct 2019, 22:26

Been keeping an eye on this thread, and something has been mentioned by the OP, limp mode, that just does not add up with my old grey matter.
Limp mode is a generic term that is usually donated by an EML which does seem to be present in the pictures posted, a safe to drive mode that prevents damage to the engine/drive train and associated systems.
However with multiple warnings from multiple systems the engine still runs, is it really in limp mode ??
So the nagging doubt in my head is that a Garage that says it is a French Car Specialist has decided that a very expensive part, even if bought on line for half the price, will be happy to remove the current part and replace it with the OP's new part, happy to charge labour and safe in the knowledge that if the problem remains they can turn round and say not our problem Guv, your part we just fitted it ???
Multiple dash/display faults cannot be caused by an ABS fault, it just does not make any logical sense.
If they are so certain that it is the ABS ECU then i would ask them to buy it, they fit it, and if it does not fix the issue they stand the costs, both parts and labour, my guess is they will refuse

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Re: Citroen C4 vtr+

Post by GiveMeABreak » 18 Oct 2019, 23:03

Yes Colin, limp mode or more precisely back up mode is when the engine ECU generally limits power to prevent damage to engine or de-pollution systems until the significant fault is corrected. It will not put all these warnings up - and will not put each of the various gauges into backup mode.

There is something else going on. I have had a look at this briefly, but had to leave it as something came up that I had to deal with. My research was getting a bit more involved as there are 3 CAN data networks involved - Body CAN, Comfort CAN and the Intersystems CAN - but each not directly related to each other - only that they of course all end up at the BSI and / or Engine Fuse Box.

So I will need to look at multiple diagrams to see why, for example, the oil and temperature gauges that are in backup mode and also the tachomter display (dashes) are not functioning and what the link is to the basic ABS module (which is a lot less involved than a combined ABS / ESP ECU which the OP doesn't have).

I'll get back on it tomorrow.

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Re: Citroen C4 vtr+

Post by admiral51 » 19 Oct 2019, 08:33

Have you tried to reset the BSI ?
If the various ECU have stored a fault then maybe a reset would clear some of them ?
BSI Reset Procedure

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Re: Citroen C4 vtr+

Post by Gramps1970 » 21 Oct 2019, 08:54

Guys thanks for the I put, only now seeing your posts. Will try the Bsi reset over the next couple of days

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Re: Citroen C4 vtr+

Post by Gramps1970 » 25 Oct 2019, 07:07

Tried reset on Bsi, problem still the same

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Re: Citroen C4 vtr+

Post by Gramps1970 » 03 Nov 2019, 22:12

This car is getting on my nerves, don't know which is the best to do, abs module or engine fuse box?