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Electrical Nightmare

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c6kev   
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,

Kevin
Trainman   
Tue Dec 22 2015, 10:54pm

Joined: Apr 12 2010
Member No: #86
Location: Penwortham
Excellent news Kev.
C6Dave   
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?
Website
JFK6_6   
Fri Jul 05 2024, 05:24pm
Joined: Jul 05 2024
Member No: #5565
Location: warsaw
Hello guys. I'm new here, and this is my first comment. I hope to revive this thread to ask for some help and guidance if possible. I live in Poland and c6 is almost a unicorn. Mechanics are not very available or have the insight to fix correctly the issues, and usually they try to postpone any real fix by exchanging part by part up to a point they give up (my personal experience).

I have my 2009 2.7 HDI with almost all the symptoms about the errors displayed, but no physical symptoms as I can notice. I also read from a previous post that send me here that maybe by adding air pressure into tires will might fix the issue ( :D ) which I don't believe, and I came straight to the source, this post!

The issue is that I was thinking to start by checking the connectors, to dry them and see if there is any change in the errors, BUT I have no idea where to find them. I don't know where is located both abs ecu as well esp ecu.

That's why I'm here... and by the look... I'm quite lost :D

thanks in advance!
C6Dave   
Fri Jul 05 2024, 05:56pm

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
JFK6_6 wrote ...

The issue is that I was thinking to start by checking the connectors, to dry them and see if there is any change in the errors, BUT I have no idea where to find them. I don't know where is located both abs ecu as well esp ecu.


Welcome to C6 ownership

OK starting with the actual ECU locations, there is a guide in the technical document section: - Click Here -

There are some used ones listed doing a Google search - Click Here - which brings up this as the cheapest option:
- Click Here - and they will courier to Poland if needed




However, members have commented that a lot of 'used' C6 parts seem to come from Lithuania
Website
MGmike   
Fri Jul 05 2024, 08:30pm

Joined: May 21 2017
Member No: #3151
Location: South Queensferry


The ABS and ESP modules are one and the same. It's all part of the ABS Pump block mounted to the left chassis rail below the under bonnet fuses/electrics.

The module in C6Dave's picture is the Dynamic Stability Control module and believe this is mounted below the centre console but I'm not 100% on that

If you post a list of the error codes we can review and advise on possible course of action.
JFK6_6   
Sat Jul 06 2024, 12:00pm
Joined: Jul 05 2024
Member No: #5565
Location: warsaw
Thank you so much for quick reply. I download the ecu location, but I only get some numbers, not the name for each ecu. If this conditions of this post are the source of my problem, I guess that all started with a water burst from the reservoir (it was wrongly closed) and all the area around the coolant reservoir and under the power steering reservoir is full of oily liquid (water with some thin layer of oil) spread everywhere.

I think i could recognize abs pump (I'm not sure, I'm not skilled in this) and it seems to be divided into left and right. The left has a small grey plug in the middle and on top is round, the right has a big black square plug and on top a square box. Am I in the right place?

C6Dave   
Sat Jul 06 2024, 01:14pm

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
If there is water etc. over any of the engine bay connectors, the 1st thing to do is pull any you can see apart 1 X 1 and dry and spray with electrical cleaner, then re-connect.

Moisture on the electrics is never good.
Website
JFK6_6   
Sat Jul 06 2024, 01:24pm
Joined: Jul 05 2024
Member No: #5565
Location: warsaw
MGmike wrote ...



The ABS and ESP modules are one and the same. It's all part of the ABS Pump block mounted to the left chassis rail below the under bonnet fuses/electrics.

The module in C6Dave's picture is the Dynamic Stability Control module and believe this is mounted below the centre console but I'm not 100% on that

If you post a list of the error codes we can review and advise on possible course of action.


P1461
P1351
U0121

my elm device does not see more

C6Dave   
Sat Jul 06 2024, 07:10pm

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
P1351 - Glow plug / relay issue see: - Click Here -

P1461 - EGR valve issue - see: - Click Here -

U0121 - No communication with the ABS or ESP ECU / ABS ECU - given there is water/ oily residue over the connectors, clean it all up as I said before.
Website
JFK6_6   
Sat Jul 06 2024, 07:57pm
Joined: Jul 05 2024
Member No: #5565
Location: warsaw
unfortunately i guess i did something wrong in my analysis. i found this water in the left side, that came from the coolant reservoir. is there any fuse regarding the ecu esp?

Also as i could understand the abs pump is on the right side under the big black box, so now i have no idea which device is this under the steering oil reservoir.

about U0121 is there any thread related to this code error?



C6Dave wrote ...

P1351 - Glow plug / relay issue see: - Click Here -

P1461 - EGR valve issue - see: - Click Here -

U0121 - No communication with the ABS or ESP ECU / ABS ECU - given there is water/ oily residue over the connectors, clean it all up as I said before.

JFK6_6   
Sat Jul 06 2024, 08:03pm
Joined: Jul 05 2024
Member No: #5565
Location: warsaw
here i have some images. from left side where is the water and the right where i believe to be the place for ecu esp and abs.

if this is true, which device is that under the steering reservoir oil? it seems 2 devices because there are 2 different connectors.


edit: im sorry but it seems that my browser does not allow popups and even pressing the image link button does not upload the image into it, maybe i need to write some name of image between img code brackets...
JFK6_6   
Sun Jul 07 2024, 09:40pm
Joined: Jul 05 2024
Member No: #5565
Location: warsaw
ADMIN EDIT: images below






MGmike   
Mon Jul 08 2024, 12:11pm

Joined: May 21 2017
Member No: #3151
Location: South Queensferry
The unit under the LDS tank (1st image) is the suspension pump and the associated electronics. The multi plug is for the electronic control module and the other ones are for the pump motor supply & control.

The Right hand side stuff (3rd image) is the fusebox, engine ecu, gearbox ecu and buried in the bottom is the glow plug relay.

Ignore the U0121 code as this is very likely a communication message following another glitch somewhere.

The fault to focus on is the P1461 which is the rear EGR. It's unlikely to effect the cars performance but will have an impact on the engine emissions.

Once you've sorted the EGR issue you may want to look at your glow plugs before winter. Before changing the relay, measure the resistance of each plug. I'm fairly confident one or more have failed and that's what's causing the P1351

I'd also recommend getting a more comprehensive Diag tool e.g. PSA Lexia/Diagbox as a basic elm will provide limited info.
JFK6_6   
Mon Jul 08 2024, 07:07pm
Joined: Jul 05 2024
Member No: #5565
Location: warsaw
MGmike wrote ...

The unit under the LDS tank (1st image) is the suspension pump and the associated electronics. The multi plug is for the electronic control module and the other ones are for the pump motor supply & control.

The Right hand side stuff (3rd image) is the fusebox, engine ecu, gearbox ecu and buried in the bottom is the glow plug relay.

Ignore the U0121 code as this is very likely a communication message following another glitch somewhere.

The fault to focus on is the P1461 which is the rear EGR. It's unlikely to effect the cars performance but will have an impact on the engine emissions.

Once you've sorted the EGR issue you may want to look at your glow plugs before winter. Before changing the relay, measure the resistance of each plug. I'm fairly confident one or more have failed and that's what's causing the P1351

I'd also recommend getting a more comprehensive Diag tool e.g. PSA Lexia/Diagbox as a basic elm will provide limited info.



thank you for such explanation but at this moment my biggest problem is to understand why i have so many errors at once and i cant drive without a beeping every 2 seconds.
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