C8 data wire fault

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C8 data wire fault

Post by thompsonp » 08 Nov 2018, 13:17


Apologies if this is posted in the wrong place. Having finally sorted my DPF woes I now have some courage to tackle airbag lights. I have the general airbag light and also the passenger airbag deactivation. I have read fault codes using a LAUNCH OBD scanner but to be fair I sent think its that comprehensive a tool for this car. It gives me the message fault on data wires, which based on the fact I have tested the switch to be good would seem to be a likely problem. The airbag ECU under the carpet looks mint no water ingress. So I am starting to consider how I can test the wiring to see if there is a fault.

I have read on the forum problems with corrosion on the fuse box (bsi) and the under bonnet fuse box does have a clip brocken however the drains are all clear under the windscreen and the fuses look OK.

I had in mind to test the continuity between the fuse and possibly the wiring to the airbag ECU and so my question is. Has anyone does this and could you advise the procedures for doing this without damaging the car or airbag system. Also does anyone know of a wiring diagram, there isn't a Haynes manual available for this car.

Appreciate any help to sort this problem



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Re: C8 data wire fault

Post by Gibbo2286 » 08 Nov 2018, 14:00

My only experience is on the C5 but on each of the three that I've had to deal with the problem was with damage to the 'clock spring' cable in the COM 2000 unit behind the steering wheel.

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Re: C8 data wire fault

Post by thompsonp » 09 Jan 2019, 10:53

thanks Gibbo2286, I have considered the clock spring but wondered as there are no other steering wheel related faults, plus the error message regarding fault on data wire.

A little bump any other ideas regarding a wiring diagram and testing the bsi to airbag ecu. Thanks

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Re: C8 data wire fault

Post by GiveMeABreak » 09 Jan 2019, 12:39

Citroen use a specific testing device connected to the pyrotechnic components prior to testing as any powered fault finding device like an ohmmeter can trigger them.

So important to have battery disconnected and allow 10+ minutes after to allow capacitors to discharge and disconnect the wiring.

If you pop up your VIN I'll be able to put a diagram up for you - but the usual suspect is the wiring under the passenger carpet.