Citroen C8 electrical problems

[Vikis]

Hello. I have a Citroen C8 2005 2.0hdi DW10ATED4. There are a lot of problems. The previous electrician tried to fix it, but made it worse, and I can't find anything.

As I know, there were problems with the fuel pump; a 12-volt cable was directly fed to the plug from the BSM fuel pump fuse. It ran. Now, there are bigger problems. First of all, I can communicate via OBD only with the Engine ECU and additional heating, nothing else. I get these fault codes:

* P0403 EGR solenoid valve open circuit
* P1458 Coolant solenoid valve circuit open or short to ground
* P0243 Turbo electro valve circuit open or short to ground
* P1451 intake air heater electro valve circuit open or short to ground
* P1460 Coolant solenoid circuit open or short to ground
* P0403 EGR short circuit to ground

Also, I have found 4 small cables cut out from the BSM (I think). White, blue, yellow, and brownish. I can't trace these cables, where they should go, and why these cables are cut out. Does anybody have a clue where to even begin?

Thank you.

EDIT:
Can't start. No crank. Ignition works, dashboard lights work

[wheeler]

Hello. I have a Citroen C8 2005 2.0hdi DW10ATED4. There are a lot of problems. The previous electrician tried to fix it, but made it worse, and I can't find anything.

As I know, there were problems with the fuel pump; a 12-volt cable was directly fed to the plug from the BSM fuel pump fuse. It ran.

This is fine for testing but should never be done as a fix, potentially dangerous in an accident.

All those faults are screaming out BSM issue, Was it replaced?

Also, I have found 4 small cables cut out from the BSM (I think). White, blue, yellow, and brownish. I can't trace these cables, where they should go, and why these cables are cut out. Does anybody have a clue where to even begin?

I'd say these are likely to be spare repair wires found on many Citroen vehicle.
see here > viewtopic.php?p=700290&hilit=repair+wires#p700290

[Vikis]

I just changed the BSM, still the same. When turning ignition on, I can hear BSI clicking. Fuses on BSI shows 12volts. I think it could be some ground missing or CAN cut out, I have no idea what else to check

[Vikis]

Actually, after the BSM change, I now have only two fault codes:
P0380: Preheating and post-heating relay stuck.
P1458: Coolant solenoid valve circuit open or short.
But still, I cannot communicate with other modules, just the ECU and additional heating

[PaulC5]

What diagnostic tool are you using, maybe it is not able to read the other things you want to see ?

[Vikis]

I have tried Diagbox, Autel, and Launch. The problem is not communication on OBD; it is that the BSI probably isn't getting enough power. No interior lights, no radio, and no navigation. Almost nothing powers up. The dashboard is working.

I just checked, and I have no +12v at the PH1, PH2, and PP connectors on the BSI. I have it only at AA and AP. What should I check? Maxi fuses near the battery are good, getting +12v. Fuses on the BSM are good, +12v

[wheeler]

Is there power at the OBD socket

Can we assume that all fuses have been checked?

[Vikis]

Yes, there is power at the OBD socket, I can communicate with ECU and additional heating.

I once again double checked all fuses, all fuses are good, at least the fuses that I know of.
Fuses and MAXI fuses near the battery, fuses on the BSI, fuses and MAXI fuses on the BSM. All fuses themselves are good, some fuses have no voltage even with the ignition on.

[Rp0thejester]

So is the problem that the car doesn't start? Or does it start but nothing works apart from the dash? Stupid question next, is your diagbox/lexia running on Version 7.6(iirc)? Anything newer will not communicate properly with the car.

[Vikis]

Yes, the car doesn't start. It's not cranking or starting. When I turn the key, I can hear some relays clicking from under the hood, but that's all. The starter is good.

Yes, my Diagbox version is, I think, 7.66. I had no problems communicating with other cars around the same model year

[wheeler]

What is your VIN so i can have a look at some wiring diagrams

[Vikis]

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

[wheeler]

OK, so there is a lot happening here (or more correctly, not happening) so its hard to pick a starting point. Below ia sa BSI & basic injection ECU diagram.
I would probably start With the ignition on and see which fuses have power at them & which dont, Then see what ones are meant to have power and take it from there.

Also you said "The previous electrician tried to fix it, but made it worse, and I can't find anything."
So what state was the car in before the electrician worked on it & how have they 'made it worse'?

[wheeler]

Maybe also do a resistance check across the CAN H & CAN L.
On the bottom diagram they are wires 9001J & 9000J.
Could check at ABS ECU (pins 19 & 35) or at engine ECU 32 way Grey connector pins A3 & A4. You should get 60 ohms.

[Vikis]

As I know, the car was running well. Then the car stopped, probably because of the fuel pump with that direct cable. After the electrician did something, now it won't crank, start, or communicate with anything. My target is at least get it cranking, then I can search further.

I checked CAN H & CAN L, at both of ECUs, ABS and engine I get 120ohms resistance, battery disconnected. Any ideas?