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C4 Grand Picasso electrical "fun"

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TobiasBB   
Thu Mar 05 2020, 12:26pm
Member No: #55742
Joined: Mar 05 2020
Location: Denmark
Hello, new to the site (and world of elderly Citroen ownership)

This might be a bit of a story but bear with me, if you don't care for the back story, jump to below the line.

I bought a C4 Grand Picasso from 2008 with ~300.000km on it, not a new racer, but need 7 seats for my family and since money doesn't grow on trees this was our option.

On our first, slightly longer outing (20? minutes) it started beeping and doing all the symptoms known online for a faulty brake pedal sensor, cleaned it up (and gave it a brand new battery) and no glitches for a few weeks, maybe more than a month really.

A potentially unimportant snippet of information: Inspecting the oil after a bit of ownership showed it mixes coolant and oil, no big deal, I was assuming that I would need to change the 1.8L petrol to one that's gone shorter, or rebuilding this one in the summer, no rush it's not bad. maybe 100ml per tank of fuel.


On the way to work one day (raining) the ABS/ ESP light came on and every time I stopped the automatic parking brake would engage, so I turned around and crawled home.

Plugging in the computer it had an array of errors, mainly brake issues, the internet suggested it could be a supply wire for the abs/ esp computer, it had been changed previously and had a beefier fuse than the original, slightly suspicious so off came the front left wheel, and inner liner and some previous owner had fitted a plastic bag around the computer.... which was full of water.

---------------------
OK: so I ordered and installed a used ABS/ ESP computer/pump, it still threw errors so I swapped the plug over from the new pump, maybe it had water/short in it, when I had only a couple of wires left there were a difference of a couple of wires between the new and old plug... (insert a huge amount of profane swearing here, I thought I had compared and counted already)...

So back on with the old plug, it turned out the reason for the difference was the abs computer I got was from a car with automatic gearbox, mine's a manual, no good as the speed sensor is apparently different, returned it for one from a manual car -> some or the codes went away.. yay!

Then there was a remaining set of codes relating to aircon, handbrake, throttle body, cruise control, and abs/ esp... so I tried swapping the BSM box, no change, then the BSI/ECU, the BSI/ECU took a few of the abs-issues away, but not all the errors.

I have cleaned up all the ground connections I've been able to find, left and right side of the motor compartment, and by handbrake, so now I'm left with:

-----------
Current error-codes:

P0571 Incoherence between 2 stop switches (intermittent)

O1671 cruise control (intermittent)

05FF unexpected re-initialisation fault coming from the BSI (not characterized) - I'm guessing this means I pulled the power while the BSI was still powered as it's not there all the time...

C1139d fault in the calibration of the longitudinal acceleration sensor: impossible. calibration*1 (Permanent fault)

C0040 Brake pedal switch fault: coherence with the pressure sensor. Coherence (intermittent)

U1113 vehicle speed data fault. vehicle speed information missing (intermittent)

U1105 Speed of rotation of the steering wheel information fault. speed of rotation of the steering wheel information absent or lost (intermittent)

C1178 ECU internal fault not characterized (intermittent)

P08eb absence of the clock saving permanent positive. No signal (I'm guessing it's because the battery is off while I'm at work or while it's being charged)

P072F Blower fault (re-reading input). no signal - air condition

U1213 Fault absence of communication with the ESP ECU. incorrect value received (intermittent)

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Thank you for reading!
Any help as to what could be some reasonable next steps in the investigation would be much appreciated..

Kindest regards, a very frustrated biologist with not enough schooling in automotive electrical system..
- Tobias.
TriumphGuy   
Fri Mar 06 2020, 01:50am
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
What are you using to read the fault codes? Lexia/Diagbox is the best one to use and is a LOT cheaper than the professional scan tools such as the Snap On Verus/Solus.
1 User said Thank You to TriumphGuy for this Post :
 TobiasBB (06 Mar 2020 : 03:08)
TobiasBB   
Fri Mar 06 2020, 02:45am
Member No: #55742
Joined: Mar 05 2020
Location: Denmark
Hi TriumphGuy, thank you for your reply.
I am using a Launch Creader professional 229, it's a standalone device which will read most errors in most brands of vehicles which was a deciding factor when choosing as I would have had to buy a laptop or similar portable device as well.
TobiasBB   
Sat Mar 07 2020, 09:15am
Member No: #55742
Joined: Mar 05 2020
Location: Denmark
I think I've narrowed it a bit down, still not sure.

It seems to be related to the power to the BSI, when I ask it to tell me the status of the handbrake or how well it communicates the signal is lost and I have to starte the computer connection over.

So it seems I need a proper wiring diagram, will the Haynes Citroën C4 manual work for the Grand Picasso?
TriumphGuy   
Thu Mar 12 2020, 08:00am
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
As a Premier member, you can access the Technical Document Archive on the Resources tab at the top of this page. The Haynes C4 is better than nothing but I'm not sure how helpful it is in your situation.
TobiasBB   
Thu Mar 12 2020, 08:08am
Member No: #55742
Joined: Mar 05 2020
Location: Denmark
Thank you ! yes, that was why I signed up, and it allowed me to trace most wires (continuity in all), narrowing it down to either the accelerometer under the cupholder - or the handbrake ecu, in which I found a dead ladybug and loads of lady-bug droppings - so last night I cleaned the circuitboard with contact cleaner, and left it to dry overnight, and now I'm just waiting to finish work so I can put it together again to see if the "bug" have gone away..
 

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