U0140 - no communication with BCM

[noMatt]

Hello everyone,

I’m reaching out for some advice on an issue with my 2012 Citroen Jumper (Relay) 2.2 HDI (150 HP). I’m encountering an error code U0140 – No Communication with BCM.

A bit of background: the vehicle recently had some damage from a marten. Despite this, everything seems to function normally, except for an odd issue with the lights. The system keeps indicating that all lights need replacing, though they’re actually working as they should.

I’m particularly interested in getting hold of the BCM pinout so I can check both the ground and positive pins. If anyone has any other information on this or can share advice on other checks I might do, I would be incredibly grateful.

Thank you in advance for any assistance or pointers. Your expertise and insights would be much appreciated!

Kind regards,
Leon

VIN: VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

Looks like there may of been some damage that isn't always visible. This is the fault descriptor.

Fault Code:	U0140 87
Description of Fault:	Built-in systems interface Absence of communication. Fault in communication between ECUs.
Conditions for Fault to clear:	Driving for 5 min
Downgrade Modes whilst Fault is active:	Irreversible deactivation of the vehicle cruise control (Need to switch the ignition off and then on, in order to make the function available again) Deactivation of the Stop and Start function Switching on of the warning lamp and/or warning message: Warning lamp MIL
Symptoms:	Lack of power Starting problem Air conditioning cut-off Fuel gauge indication incorrect
Suspect Areas:	CAN network

The diagrams are system-specific, so each will show the relationship between a system and the BSI or the the Engine ECU.

This is for the main / dipped beam lights, which is what I think you're saying is the issue:



With the exception of the wiring codes, most of the component codes are indexed here:

PSA Electrical Diagrams - Wiring & Symbols Codes Index

[noMatt]

Thank you very much for that! Im not positive that the beam light is the issue, more in general i think the BCM is the issue. Id love to focus on the communication first:


I plan on measuring the can bus behind the BSI to see wether the cable is broken or the problem is inside of the BSI (or the can bus section of the ecus connected to the BSI). I bought myself an oscilloscope and want to try to identify the problem.

For that it would be incredibly helpfull to know how the BSI is connected to the rest of the CAN Bus not portayed in the picture. and how is everything connected to the OBD2 Data Port? Or is the BSI directly wired to the data port?

I hope im not asking for to much information, thank you very much for this forum!

Kind regards
Leon

[GiveMeABreak]

There are multiple networks - split into and prioritised into different systems, too detailed to go into here and each operating at different speeds. It's not possible to provide an overarching diagram as these are all split into sub-systems.

[noMatt]

Allright thank you very much! i was able to resolve the issue, it seemed like the can connection from the bcm to the port was bad, i was able to fix it. Now my BCM is throwing the following errors

B1007 - left hand indicator illumination fault
B1008 - right hand indicator illumination fault
U0001 CAN C - Communication Impossible

I attached images for that. I tried changing the lightbulbs for the opencircuit faults, but this didnt fix the issue (the direction lights are actually working)

One thing ive noticed while changing the lightbulbs: when removing the headlight on the passenger side (rightside because its a german car), a disconnected electric connection gets visible. But sadly only the bare adapter is present, the matching counterpart is nowhere to be seen. That might very well be the solution, but i have no clue where the adapter is meant to be connected. Maybe im just lacking some feature in the car but the connector is there anyways?
Anyways id be very intrested what this could be.

Can you provide any advise how id start to fix theese problems?
Especially im intrested for more information about the CAN C Network if that woud be possible.



Thank you so much for you help so far!


Kind regards
Leon

[GiveMeABreak]

I've just had a look for these codes and nothing is coming back (which is possible with these commercial vehicles as this one is a Ford variant).

But the CAN is not communicating in certain areas. Here is the signalling diagram that may help:




Wiring