Citroen C2 - dead electrics - No power to locks, interior light, ignition - everything dead

[napping]

I have a Citroen C2 that has dead central locking and no signs of life other than a single beep when I reconnect the battery.
All the electrics are dead, no dashboard display, no lights, etc. so checked the battery and that is fine (it reads 13v).

I've checked that although the electrics are dead, there is power getting through to the main fuse. Also, when I connect the battery there is a single bleep coming from inside the car. Nothing is displayed, there is just this single bleep when reconnecting the battery - that's the only sign of life!

The car did have this happen once before and whilst I was tracing the wires with a multimeter it corrected itself. but I never identified the cause of the electrical failure. As it did correct itself last time I don't think it's ECU corruption.

Any ideas or help appreciated

Also - is there any way to open the deadlocked passenger door without the electrics working??

[wheeler]

First thing i would do is check the main earths from the battery to the gearbox & body. Give the cables a good. Actually remove, inspect & clean the earth points. Are the maxi fuses in the under bonnet fusebox getting power at both sides?

[napping]

Checked earth points and fuses. All fuses have power both sides except for fuses - 8 (Starter), 3 (Screen wash), 12 (windscreen wiper) and 14 (Air pump?).

[Pablo]

Try connecting a jump lead from the battery negative to a known, good chassis earth.

[napping]

Good suggestion, thanks. So I tried this and still no electrics. Just a single beep when the battery is reconnected. One clue is that this happened one before and corrected itself when I ran a continuity test to the BIM and ECU. Are the solid state relays like the old magnetic relays in that they can get "stuck" open?

[napping]

Try connecting a jump lead from the battery negative to a known, good chassis earth.

Tried the suggestion of connecting a jump lead to earth (body and engine points) and still no power to locks, etc. I also tried swapping the fuse box for one known to be working and still no joy. Any suggestions on what to check next?

[ozvtr]

Are the solid state relays like the old magnetic relays in that they can get "stuck" open?

is there any way to open the deadlocked passenger door without the electrics working??

No solid state relays in the C2.

For the locks, you could remove the relevant connector at the BSI and apply 12V to the appropriate pins. Power pin 13 of the 16 pin grey connector in the BSI OR power pin 15 of the 16 pin grey connector. One will lock and one will unlock. Sorry don't know which is which.

Does the engine "turn over" when you turn the key to start? If not you have a fundamental power problem. I.E. positive or negative battery connection problem.
The starter solenoid comes straight from the key and the starter is powered directly from the battery. No electronics or black magic involved! Er...except if it's a sensodrive or auto. Then there is a problem. Is your C2 pre or post 2005?
If it does turn over, start looking a the BSI. Loss of power or faulty. Most likely loss of power. Fuse or corroded connector at the maxi fuses under the BSM. Grey 2 pin connector at the BSI.

Again is your car pre or post 2005 and is it a manual?

[napping]

No solid state relays in the C2.

For the locks, you could remove the relevant connector at the BSI and apply 12V to the appropriate pins. Power pin 13 of the 16 pin grey connector in the BSI OR power pin 15 of the 16 pin grey connector. One will lock and one will unlock. Sorry don't know which is which.

Does the engine "turn over" when you turn the key to start? If not you have a fundamental power problem. I.E. positive or negative battery connection problem.
The starter solenoid comes straight from the key and the starter is powered directly from the battery. No electronics or black magic involved! Er...except if it's a sensodrive or auto. Then there is a problem. Is your C2 pre or post 2005?
If it does turn over, start looking a the BSI. Loss of power or faulty. Most likely loss of power. Fuse or corroded connector at the maxi fuses under the BSM. Grey 2 pin connector at the BSI.

Again is your car pre or post 2005 and is it a manual?

Thanks for the advice. It's a 2006 model with a manual gearbox. The engine doesn't turn over on the key and there is no "click" from the starter solenoid.

[ozvtr]

Thanks for the advice. It's a 2006 model with a manual gearbox. The engine doesn't turn over on the key and there is no "click" from the starter solenoid.

OK. That's good and bad news. The bad news is I don't have a circuit diagram for the MK2 and you can't do what I was going to suggest with the starter solenoid. The good news is your car is a manual. As I said the power for the starter solenoid comes directly from the ignition switch. Auto boxes and sensodrive boxes have a cut out relay to the starter solenoid but the manual box goes straight through to the starter. So it should have turned over! On the surface it seems you are not getting power to the ignition switch. Conveniently that same power line feeds the "wake up" control to the BSI and BSM.
Ok, I have made a BIG assumption that something is powering up and "beeping" when you attach the battery. As you said, the only sign of life. So I am assuming the ECUs are getting power but not waking up when the ignition key is turned. This leaves only one circuit that could cause that fault.
Up at the steering column there is a big green connector with a red locking tab.The wires go up to the ignition switch. Pull the connector apart or back probe the contacts with your multi meter if you can. On the loom side (not the ignition switch side) connector, one of the 3 pins should have a permanent 12V from the battery. The other 2 should be dead (or maybe low volts). One goes back to the starter and the other goes back to power some of the BSM fuses. Find a good chassis ground in the foot well so you are sure to get a reliable reading from the multimeter. The steering column might be OK for a ground.
If you get nothing on any of the pins the problem is probably the maxi fuse or the wiring between there and the ignition switch.
If you get power on one of the pins then the problem might be the ignition switch.
The maxi fuses are located underneath the BSM in the engine bay. You need to disconnect the battery positive. Undo the nut on the stud of the BSM that goes to the battery. Remove the BSM. It's a pain in the @$$ but it is held in place by clips around the perimeter of the BSM and the maxi fuses holder is clipped to the underside of the BSM.

[ozvtr]

Nope! I've been thinking about it.
That doesn't explain why the instrument cluster and interior light don't come on when you open the door!!!
And what beeps when you connect the battery?
Sorry but I'm going back to a fundamental power or ground problem.
Check for power at the green connector but I bet you don't get a reading.
Check for power at the nut that I mentioned on the stud of the BSM. Check between that nut and the negative terminal. The actual battery terminal, not the clamp. If you have power at the nut but no power at the ignition switch, then you have a problem with the maxi fuse power distribution...some how. Pull the BSM out and inspect the maxi fuse holder and wiring.
If you don't have power at the nut, check the positive battery connection for tightness or corrosion. Check the cable that goes from the battery positive to the BSM.
Put your multimeter leads from the battery negative terminal (the actual terminal not the clamp) to the chassis. Then move your lead from the chassis to a metal part of the engine. If you get a voltage reading at all, check and clean the battery terminal. Check the earth straps...again.
I cant see how the starter wont work but something inside the car is beeping. If the starter wont work then virtually nothing should work (in this case)!!!
Even if the battery is "flat", if it can supply voltage above, say 10V, then the instrument cluster should come on and you say it's supplying 13V.

[ozvtr]

Checked earth points and fuses. All fuses have power both sides except for fuses - 8 (Starter), 3 (Screen wash), 12 (windscreen wiper) and 14 (Air pump?).

Arrggghhh! This thing is driving me mad!!! I am still not addressing all the symptoms!

If you have power at the BSM fuses then power is getting from the battery to the BSM. So the cable from the battery to the BSM is OK. Power for the above fuses will come from the ignition switch in the 'accessory' position. But the power for the ignition switch comes from a maxi fuse, as I mentioned above.
Do you get power to those fuses when the ignition is turned on? I bet you don't. Again, this will be the same power that runs the starter solenoid and that's not working.
The "starter" fuse is for the starter relay I mentioned before, not relevant to you. The air pump is for turbo charged engines (is yours a diesel? Not relevant in this case).
The maxi fuses also provide 2 sources of power to the BSI, which in turn feeds all the cabin devices.
There are a number of maxi fuses involved in the systems. A failure of just one will not cause all your symptoms but a failure of all of them will. But knowing what I know about the Maxi fuses and the power distribution system I cant think how this could happen.
I am thinking there is a problem with the maxi fuse distribution...I don't know what, but it's all that I've got...again.
I can only suggest removing the BSM and inspecting the maxi fuse panel.
...For the last time.

This is what the maxi fuse block looks like when you remove the BSM.

[wheeler]

Can you try disconnecting the plug on the yellow connector shown below (the plug iteslf will probably be grey).
Give Pin 2 a 12v feed & see if the starter operates. I think the pins are numbered right to left as you look at it but please check.
PLEASE ENSURE THE GEARBOX IS IN NEUTRAL BEFORE DOING THIS

[napping]

Give Pin 2 a 12v feed & see if the starter operates. I think the pins are numbered right to left as you look at it but please check.
PLEASE ENSURE THE GEARBOX IS IN NEUTRAL BEFORE DOING THIS

Before I try this can I double-check that you're suggesting connecting 12v to the pin on the fuse box side OR is it the pin hole on the connector that gets the 12v?

[wheeler]

Harness side

[napping]

Harness side

I can only suggest removing the BSM and inspecting the maxi fuse panel.
This is what the maxi fuse block looks like when you remove the BSM.

Earlier I removed the BSM to inspect the maxi fuses and tested each fuse to see if any were blown - none were. So far I haven't pulled any of the maxi fuses out as they felt well seated and they didn't want to budge. Perhaps the next step is to test for an open circuit to the BSI - but without a wiring diagram for the Mk2 I fear prodding with a multimeter could do more harm than good!

I bought a Haynes manual specifically for a wiring diagram, but the manual only shows the Mk1 BSM/BSI - and despite trawling the net I have not managed to track one down yet.