any advice please, undiagnosed electrical faults!

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My Name: johnh

Contributor
Posts: 11
Joined: Fri Jun 13, 2014 6:34 pm
Model: C3 2006-2009, Facelift model
Year: 2006 (06)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 34000
Trim Level: Desire
Gearbox: Manual 5 speed
DPF: No

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Further to earlier posts, I decided that taking the dealer to court was a waste of time as I couldn't afford a new car and I would have ended up getting a judgement in my favour but probably have to chase him for the money!!!
Anyways I have a citroen c3 1.4 desire petrol 2006: I have every single sensor fault available coming up on the dash lights and onboard computer and lately the electronic speedo has stopped working intermittently along with the rev counter, whenever I stop the car it wont even crank over until I have left it for around 15mins.
Apparantly there is an abs fault, seatbelt/airbag fault, pollution filter fault, sidelamp fault, serv light comes on with sidelamp fault etc etc.
First time it happened I parked it up and noticed that the neutral battery connector was hanging off, I tightened it up but it went into eco mode and I called the AA, the AA guy stated the obvious that the error messages were due to the battery lead hanging off the battery post, he checked battery with a volt meter and said it was fine, checked that the alternator was charging and it apparently was, we left the ignition off for 10 mins and it cranked over, although his diagnostics couldn't remove the error codes, so I had a local mechanic to remove them using the citroen software, I told the mechanic that the car commonly came up with "sidelamp error" even though the bulbs were fine, this guy used to work for Citroen and explained about an earthing issue on the rear light clusters and I would have to book it in next week to get it sorted.
Yesterday it all happened again, AA were called out again, this guy actually done a proper battery check and the printout stated replace battery which I did and it was ok....till this afternoon, same thing again, error codes persistant fault beeping, so called AA out again!
This AA guy took every earth lead from the body and cleaned the terminals etc, he even checked for the common brake cluster earth wire fault but all appeared fine, give him his due, he didn't like leaving me with the car with the problems still there and stayed over an hour and half to try and resolve the issues with no joy, however on his leaving, all the dash lights had gone off so I took it for a drive, got to 40mph, then the sidelamp error fault appeared along with abs, airbag etc etc.
If its not a battery / alternator fault or light cluster earth fault, could anyone please advise if you have any ideas?!

Many thanks
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My Name: C3driver52

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Joined: Sat Apr 30, 2011 7:40 pm
Model: C3 2002-2005, Original shape model
Year: 2003 (03)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 79984
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: TU3 (75 PS)
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Hi johnh,
johnh wrote:Further to earlier posts,
https://citroenc3owners.com/citroen-c3-q ... t1091.html
Did you manage to identify the part, or get a picture of it?

johnh wrote: I decided that taking the dealer to court was a waste of time as I couldn't afford a new car and I would have ended up getting a judgement in my favour but probably have to chase him for the money!!!
https://citroenc3owners.com/citroen-c3-q ... t1105.html

Well done with your win!
johnh wrote:whenever I stop the car it wont even crank over until I have left it for around 15mins.
Sounds like starter motor, starter wiring?
johnh wrote:Apparantly there is an abs fault, seatbelt/airbag fault, pollution filter fault, sidelamp fault, serv light comes on with sidelamp fault etc etc.
ABS and seatbelt faults can all come from a single source, the road speed sensor. Side lamp fault has been covered here (thanks to trumpycam).
johnh wrote: although his diagnostics couldn't remove the error codes, so I had a local mechanic to remove them using the citroen software,
Deleting or removing the codes without noting them or making a record doesn't help identify the faults recorded. The codes are the messenger from the ECU. A record of them should be made before deleting them, then re-read the codes to see what is new and then investigate or diagnose the remaining codes.
johnh wrote: I told the mechanic that the car commonly came up with "sidelamp error" even though the bulbs were fine, this guy used to work for Citroen and explained about an earthing issue on the rear light clusters and I would have to book it in next week to get it sorted.
Yes, it seems to be a common problem, the solution is here (thanks to trumpycam).
johnh wrote:error codes persistant fault beeping, so called AA out again!
The codes are your 'key' to the problems. Its the only way the ECUs can talk to the outside world, they should be embraced and recorded. The codes can help identify where the fault is. Just deleting them won't fix the broken part.
johnh wrote:This AA guy took every earth lead from the body and cleaned the terminals etc, he even checked for the common brake cluster earth wire fault but all appeared fine, give him his due, he didn't like leaving me with the car with the problems still there and stayed over an hour and half to try and resolve the issues with no joy, however on his leaving, all the dash lights had gone off so I took it for a drive, got to 40mph, then the sidelamp error fault appeared along with abs, airbag etc etc.
I would have done the earth lead for the rear clusters fix anyway. Its only quick and one of the cheaper repairs. I wonder if the codes that keep getting deleted are 'vehicle road speed' or 'abs wheel sensor' faults? I would imagine they are.... ;)
johnh wrote:If its not a battery / alternator fault or light cluster earth fault, could anyone please advise if you have any ideas?!
I would say 2 faults:
1. earth lead to the rear clusters/rear cluster wiring/rear cluster lamps
2. ABS wheel sensor/abs ring fault, wiring to the ABS wheel sensor.

Read the codes to see if I got the wheel sensor one right :) You can diagnose the ABS system with the lexia kit and a laptop, but I suggest you have a look at the Lexia topic for the C3 before taking the plunge.
My Name: johnh

Contributor
Posts: 11
Joined: Fri Jun 13, 2014 6:34 pm
Model: C3 2006-2009, Facelift model
Year: 2006 (06)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 34000
Trim Level: Desire
Gearbox: Manual 5 speed
DPF: No

Post

Hi, many thanks for your info, the codes that were read by the AA on 2 occasions are as follows

u1000 can data bus ecm - no communication
u1003 can data bus no communication
u1003+ - no communication

at the time the AA guys said it something to do with the canvas??
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My Name: C3driver52

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Posts: 1940
Joined: Sat Apr 30, 2011 7:40 pm
Model: C3 2002-2005, Original shape model
Year: 2003 (03)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 79984
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: TU3 (75 PS)
Has thanked: 114 times
Been thanked: 67 times

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johnh wrote:Hi, many thanks for your info, the codes that were read by the AA on 2 occasions are as follows

u1000 can data bus ecm - no communication
u1003 can data bus no communication
u1003+ - no communication

at the time the AA guys said it something to do with the canvas??
Thank for the codes, they are a beacon pointing at your problem.

U codes point to network errors (CAN Bus) which is the twisted wire pairs that allow communication between ECUs and some devices. This could be a wiring fault on the CAN Bus or, possibly some faulty CAN device.

Its nice to see U codes in the wild, its normally P codes that do the rounds on the forum.

Your U1xxx codes are Citroen specific network (CAN) faults, for which, if I was diagnosing the faults, I would use only the citroen workshop tool (lexia/diagbox). Generic tools may not be 100% for obscure U1xxx codes. Its just not worth the hassle of barking up the wrong tree after being misled by non specific test equipment.


Diagnosing would include looking at the wiring to each ABS sensor, all the way back to the ECU, then if they are OK check the rest of the CAN bus wiring. I would be looking for a chafed cable on the ABS wheel sensor circuit, but I would then look for any other damage on the bus.

Oh, the 'canvas' is the 'CAN bus' :D you can find out about it here


The CAN BUS comes to the engine ECU

engine ECU for CAN BUS on citroen C3
engine ECU for CAN BUS on citroen C3
and the BSI

Citroen C3 BSI
Citroen C3 BSI
Usually as a twisted pair of conductors.
Twisted Pair on the CAN BUS
Twisted Pair on the CAN BUS
My Name: johnh

Contributor
Posts: 11
Joined: Fri Jun 13, 2014 6:34 pm
Model: C3 2006-2009, Facelift model
Year: 2006 (06)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 34000
Trim Level: Desire
Gearbox: Manual 5 speed
DPF: No

Post

Thanks very much for your info C3driver52, I noticed that the car failed an mot last april due to the abs light being on, maybe the dealer had messed around with things to get the dashlight off??
So the stated "U" codes would explain the abs light and the "stop, brake system fault " message, but what about all of the others that are being thrown up too i.e. airbag, seatbelt tensioner, pollution filter, sidelamp error etc?
I had the airbag and seatbelt lights and sidelamp faults come on a few days after getting the car, I did notice that there was 3 connector blocks hanging down from under the glove box, one of them looking the same as the seatbelt sensor under the passenger seat (grey slim connector and plug) anyways I relocated them back to their position, they were supposed to be held up with firtree type connectors with a slot and straight away the airbag and seatbelt lights disappeared from the dash, I thought that's what the problem was! I never had any problems with them for over a month, till Tuesday when I got the whole dashlight errors in succession, this was due to negative terminal hanging off the battery post!
I then assumed that all of the faults were because of this battery issue, so I got new battery, worked ok for a day, then same issues, AA bloke today cleaned all body earth conns up and it was ok for an hr, I have tried the bsi reset procedure, this does delete the lights on the dash but when driving anything over 50/60mph then the lights re-appear :(
**just nipped out to look at the canbus wires. there is green heatshrink from the end of the sheath to approx 1 inch before they go into connector block, is this normal? Also is there supposed to be a cover over the 3 ecu plugs ? **
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My Name: C3driver52

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Posts: 1940
Joined: Sat Apr 30, 2011 7:40 pm
Model: C3 2002-2005, Original shape model
Year: 2003 (03)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 79984
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: TU3 (75 PS)
Has thanked: 114 times
Been thanked: 67 times

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johnh wrote:I noticed that the car failed an mot last april due to the abs light being on, maybe the dealer had messed around with things to get the dashlight off??
You never know. If there is a fault that could affect the ABS system, then the ABS light should stay on as a warning. Its often wheel sensors and their rings that give trouble because of their positions on the car, but it could be cause by many other things.

johnh wrote:So the stated "U" codes would explain the abs light and the "stop, brake system fault " message, but what about all of the others that are being thrown up too i.e. airbag, seatbelt tensioner, pollution filter, sidelamp error etc?
U codes could cover airbag, abs, sealbelt pre tensioner, power steering, speedo, dashboard and possibly pollution filter and sidelight error. But there will be other codes saved for all of these with possibly the exception of sidelight error. For the side light one, I would just do the fix for it anyway. At least then you know its not the common fault. Hey, it may even cure the other CAN faults?
johnh wrote:I had the airbag and seatbelt lights and sidelamp faults come on a few days after getting the car, I did notice that there was 3 connector blocks hanging down from under the glove box, one of them looking the same as the seatbelt sensor under the passenger seat (grey slim connector and plug) anyways I relocated them back to their position, they were supposed to be held up with firtree type connectors with a slot and straight away the airbag and seatbelt lights disappeared from the dash, I thought that's what the problem was!
Its always a worry when the car has been taken apart and not put back together correctly :? You just don't know what else is lurking.
johnh wrote:I have tried the bsi reset procedure, this does delete the lights on the dash but when driving anything over 50/60mph then the lighs re-appear :(
Which would point to wheel sensor or speed sensor. Just deleting the codes all the time doesn't repair the faulty part on the car and the codes will keep coming back because the faulty part is still on the car.

It would be interesting to see what code you get stored when driving over 50/60mph.
My Name: johnh

Contributor
Posts: 11
Joined: Fri Jun 13, 2014 6:34 pm
Model: C3 2006-2009, Facelift model
Year: 2006 (06)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 34000
Trim Level: Desire
Gearbox: Manual 5 speed
DPF: No

Post

I am really interested to find out what the problem is too, along with the poor AA guy, he was mortified that he couldn't solve the issue and had to get back on the road to help other breakdowns, he said that in cases like this, he wished he was back on the tools in a garage as he would have enjoyed solving the issue...bless him :)
Ive found a local firm of auto electricians that has citroen dealership experience amongst others, bmw etc, I think im more inclined to use an auto eleccy than a general workshop mechanic with this issue, its gotta be cheaper than Citroen dealership :)
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My Name: C3driver52

Guru
Posts: 1940
Joined: Sat Apr 30, 2011 7:40 pm
Model: C3 2002-2005, Original shape model
Year: 2003 (03)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 79984
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: TU3 (75 PS)
Has thanked: 114 times
Been thanked: 67 times

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johnh wrote: Ive found a local firm of auto electricians that has citroen dealership experience amongst others, bmw etc, I think im more inclined to use an auto eleccy than a general workshop mechanic with this issue, its gotta be cheaper than Citroen dealership :)
I agree, this is a job for a technician and not a mechanic :)

Good luck. Let us know what the auto electricians say. Those U codes and P codes are invaluable for diagnosis.
My Name: johnh

Contributor
Posts: 11
Joined: Fri Jun 13, 2014 6:34 pm
Model: C3 2006-2009, Facelift model
Year: 2006 (06)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 34000
Trim Level: Desire
Gearbox: Manual 5 speed
DPF: No

Post

Will keep you posted, even the AA guy left me his moby number to let him know if I found the issue, Just to emphasise my previous questions... is it normal to have a length of heatshrink on the canbus cable and should there be some sort of plastic cover for the connectors that plug into the ecu or is it all meant to be exposed as per your pic ?

many thanks :)
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My Name: C3driver52

Guru
Posts: 1940
Joined: Sat Apr 30, 2011 7:40 pm
Model: C3 2002-2005, Original shape model
Year: 2003 (03)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 79984
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: TU3 (75 PS)
Has thanked: 114 times
Been thanked: 67 times

Post

johnh wrote:Will keep you posted, even the AA guy left me his moby number to let him know if I found the issue, Just to emphasise my previous questions... is it normal to have a length of heatshrink on the canbus cable and should there be some sort of plastic cover for the connectors that plug into the ecu or is it all meant to be exposed as per your pic ?

many thanks :)
Looking at the engine bay in its normal running condition, you can't see the engine ECU because its covered by the battery cover, as in the picture.

Battery cover fitted on a Citroen C3
Battery cover fitted on a Citroen C3

Remove the battery cover to expose the battery and engine ecu connections

Cover removed showing engine ECU connections on a Citroen C3
Cover removed showing engine ECU connections on a Citroen C3




Engine ECU with heatshrink on one of the cables - like this? Looks odd, but seems factory fitted.
heat shrink on wires to engine ECU on a citroen C3
heat shrink on wires to engine ECU on a citroen C3
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