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Electrical Nightmare

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Author Post
Tue Dec 22 2015, 10:00pm
Joined: Dec 02 2013
Member No: #1508
Location: Wales
The good news is that this story has a happy ending. Initial indications, however, were that diagnosis and cure might cost more than the value of the car.

My local auto electrician and my friendly Citroen service manager both pointed me in expensive and incorrect directions, but the archives of this forum produced a simple and effective cure. My thanks to Alanr7 for passing on his hard earned knowledge (3 ½ months and two dealers to effect a diagnosis).

It started with multiple warning messages:

· Suspension faulty warning
· Automatic headlight setting fault warning
· Handbrake faulty warning
· Mobile deflector faulty warning
· Directional headlight faulty warning
· Brake system faulty warning
· ESP/ASR system faulty warning
· Airbag or seat belt pretensioner faulty
· Gearbox faulty
· Suspension faulty
· Speed control system faulty
· Parking brake cable fault

Accompanied by physical symptoms:

· Heavy steering
· Suspension very bouncy
· Gearbox offering a choice of two ratios – 3rd or reverse, both engaged with the subtlety of a sledge hammer
· Rear spoiler fully raised
· After turning off, the engine runs on for one or two minutes
· Intermittent chattering of Park release solenoid
· Unable to start engine while solenoid is chattering
· Parking brake inoperable
· No cruise control
· Intermittent loss of speedo and tacho readings

Lexia produced a hundred or more logged faults (within minutes of clearing the whole log), most of which were failures of the various ECUs to communicate with one another. The remainder were related to speed information (or lack of it) or incorrect brake switch data.

Many postings on the forum point to a replacement brake switch curing the warning message problems, but that wasn’t enough to cure this extended list of problems. The solution for these required a replacement of the ABS ECU block.

My guess is that only the ABS ECU was actually required, but it came as a complete assembly from a breakers and I fitted a new brake switch as a cheap option (more in hope than expectation).

After a 350 mile test drive (half of it with a one tonne trailer, I am pretty confident that the nightmare is finally over.

Hopefully the next owner to suffer this nightmare will stumble over this posting in time to save their wallet and patience from a long and difficult diagnosis.

Well worth the cost of the second hand part to enjoy such refinement for today's journey. And then there is tomorrow, and the next day, and...

Happy Christmas to all C6ers,

12 User said Thank You to c6kev for this Post :
 Trainman (22 December 2015) , e3steve (23 December 2015) , gbl (23 December 2015) , 321dave (23 December 2015) , davidlaver (23 December 2015) , Leo (23 December 2015) , Tjensen (23 December 2015) , Cisco (23 December 2015) , eke (24 December 2015) , David K (26 December 2015) , userpco (31 January 2016) , Norman (09 February 2016)
Tue Dec 22 2015, 10:54pm

Joined: Apr 12 2010
Member No: #86
Location: Penwortham
Excellent news Kev.
Wed Dec 23 2015, 09:39am

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
For Info: early on in the life of the C4 (built at the same time as the C6) there was a recall for the ABS block.

Basically capillary action was allowing water into the electrics. Under re call the ABS block was tested and if faulty, replaced, if not the wiring/connectors were re sealed.

Maybe cleaning and sealing the connectors is something owners of the C6 should look at?
3 User said Thank You to C6Dave for this Post :
 cruiserphil (23 December 2015) , e3steve (24 December 2015) , userpco (31 January 2016)

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