Crank no start 2006 C5 V6

[ekaftan]

I was driving my car home when I lost almost all power and the check engine light started flashing. I managed to limp the car home, opened the hood and found nothing obviously wrong.

I shut down the engine, went inside to get a generic OBD reader to get codes and could not get the car started again.

The code reader shows every injector and sensor as 'circuit low' and the fuel pump does not come on... So I can assume I lost some kind of power to the ECU or from the ECU to the systems. Fuel pump also does not come on when I unlock the car as it used to.

Is this a 'known' problem? Is there a fuse or relay that goes bad? I replaced the fuel pump a week ago, but now no power gets to it and the pump fuse is not blown so I doubt is bad...I will test it tomorrow though.

Side question: were can I get a wiring diagram for this car? Its ok if I have to buy it.

Thanks!

[xantia_v6]

Is this the ES9J4S engine? I would be suspecting a fault with the engine bay fuse box (BSM), but check ALL of the fuses first.

[wheeler]

Agreed (assuming all fuses are OK) the under bonnet fuse box would be my first suspect here. The power to the injectors & fuel pump are normally supplied from the same relay inside the fusebox. Might be worth unplugging it & checking for any signs or water ingress.
To get the correct wiring diagram for your car we would need your VIN.

[xantia_v6]

VIN here:

viewtopic.php?p=729880#p729880

[ekaftan]

VIN here:

viewtopic.php?p=729880#p729880

Yes. Thanks. Thanks my VIN in that post.

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

[wheeler]

The Injectors & fuel pump share the same outputs.

[ekaftan]

The Injectors & fuel pump share the same outputs.

You can diagnose a car 11000 kmts away. Could this be a world record?

12Volts direct to fuse 10 and the car runs perfectly.

I checked all fuses and probed fuses 5 and 10 while cranking and got nothing.

Now what? a new fuse box? can a used one be installed? or are they one time only program like the in car BCM?

I am rather handy with a soldering iron so maybe I can get in there and replace the relay. Could it be done?

Thanks!

ps. Here I am

[ekaftan]

Side question... does this car have an inertia switch?

this problem started after going over a sleeping policeman or road bump at speed...

Maybe its something simpler like that.

[wheeler]

No inertia switch fitted to this car.
The under bonnet fusebox (BSM) is not programmed to the car so a used one (from the same spec of car) can be installed no problem.
If you are handy with a soldering iron then the relays should be replaceable no problem I would think.

[ekaftan]

I am repairing or trying to repair the BSM today and when I removed it I found this wires dangling next to it, way too nicely cut to be something I did manhandling the BSM to take it out.... but weird nevertheless.

Any idea where are they from?

Thanks!

[ekaftan]

Car is running now...

I managed to repair the BSM in about two hours taking it slowly and with minimal soldering.

First, I removed the existing fuel pump / injection relay from the box.

In this picture you can see the coil pins and the burned-looking hole just above it is where +12v comes from the big battery bus. The relay's frame is where power goes out to the fuses.

After cleaning the pins I soldered the wires that will go to pins 85 and 86 to the external relay (polarity does not matter).

Power will come directly from the bus using a round terminal and go into the BSM using a fuse adapter thats normally used to get power out for accesories.

I added a 40amp fuse between the wire that delivers power to the adapter and the bottom pin of fuse 10 on the box, and reused the 30amp fuse on the adapter to deliver power to the injectors. Power to the fuel pump goes through the 40amp fuse to the BSM through fuse 10 and comes out vie the normal 15amp fuse.

Final picture installed on the car. With the covers on it looks 100% stock. Total cost was about US$20 + my time.

Many thanks for the help and information. I hope this summary can help somebody else.

BSM-L04-00

[xantia_v6]

Good job.

Those cut wires are factory fitted 'spares', the other ends are near the BSI behind the dashboard.

[CitroJim]

Excellent work

[ekaftan]

The Injectors & fuel pump share the same outputs.

Hi!

Its me. Again.

Car now won't crank. Battery was flat so I used a jump pack. Car started normally but stalled after about a minute and did not restart.

I have nothing but a very faint click coming from the heater panel when I put the key to the start position.

ECM is online as I get a check engine light.

BSM seems offline. Fuel pump also not coming on.

Any ideas? All fuses look fine... I will re check them one by one anyway....

Is there a way to jump the starter from the BSM?

Thanks!

[wheeler]

Is there a way to jump the starter from the BSM?

Thanks!

Yes, pin 2 of the 5 way yellow connector. Be aware that the connector is actually grey on the outside but the yellow part is underneath.