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

[napping]

Just went to start checking earths..... Reconnected the battery....... The car burst into life and unlocked the deadlocks!

I opened the door and the interior light came on - but just for a couple of seconds.
Then back to square one - everything was dead again!

This suggests to me that the BSI itself still works and the problem is more likely to be power, earths or signal to BSI wires - so just about anything!

As ozvtr says, back to pin by pin wire tracing.

[Pablo]

Not looking back through all the posts but......I guess you have tried a different battery? I've come across the odd few, particularly on trucks, which have had a broken connection under the post causing an intermittent connection.

Clutching at straws probably but worth a mention.

[ozvtr]

Just went to start checking earths..... Reconnected the battery....... The car burst into life and unlocked the deadlocks!

I opened the door and the interior light came on - but just for a couple of seconds.
Then back to square one - everything was dead again!

This suggests to me that the BSI itself still works and the problem is more likely to be power, earths or signal to BSI wires - so just about anything!

As ozvtr says, back to pin by pin wire tracing.

Well this is good and bad news.

Good: it's not a permanent fault...it can be repaired!

Bad: you have to find it!

Is it cold there at the moment? Just a few potential things that could go wrong with the BSI and give these symptoms. Bad power regulator/semiconductor. They usually fail when they get hot/warm. Bad solder joint. Solder joint just makes contact until it warms up (current passing through it).

Although if it did this once before I doubt it's a semiconductor. They don't just start working again (er...usually).

Sounds like perhaps a point contact problem, or lack there of! Like a broken wire, bad connection or solder joint.

You could try pulling on the wiring and connectors?

Give the BSI a few good thumps!! LOL, that'll learn it!!

[napping]

Not looking back through all the posts but......I guess you have tried a different battery?

I sent 12v to the starter solenoid and the engine turned over freely - confirming the battery is fine.

[napping]

Sounds like perhaps a point contact problem, or lack there of! Like a broken wire, bad connection or solder joint.
You could try pulling on the wiring and connectors?

Question: If there's a bad contact on the ECU pins could it cause the BSI to remain asleep?
I hear that the ECU plugs are prone to problems, especially for cars that aren't in daily use. The ECU plugs are very exposed and I suspect the car has been subjected to more than its fair share of condensation due to lack of use during the pandemic.

[Hell Razor5543]

I wonder what would happen if you were to spray some contact cleaner into all of the plugs, and then unplug them and plug them back in several times? I have experienced a build-up of tarnish on the blades of a fuse that caused my rear wiper to go intermittent. Although I didn't use any contact cleaner, unplugging it and plugging it in several times cleaned the tarnish off, and the wiper behaved itself.

[napping]

I wonder what would happen if you were to spray some contact cleaner into all of the plugs, and then unplug them and plug them back in several times?

Worth a try! If I do one plug at a time, there's a chance I can find an offending plug I've tried pulling, pushing, wiggling and swearing at the wires - so hitting them with contact cleaner can't do any harm

[Hell Razor5543]

But make sure to plug/unplug each one several times, as the action should help remove any dirt (ably assisted by the contact cleaner).

[xantia_v6]

My guess now would be that there is a faulty solder joint on one of the PCBs that handles the main feeds.

Either try another BSI, or dismantle and inspect carefully with a magnifying glass.

[napping]

My guess now would be that there is a faulty solder joint on one of the PCBs that handles the main feeds.
Either try another BSI, or dismantle and inspect carefully with a magnifying glass.

Ok - next plan of attack will be; double check earths , examine and clean each plug and its pins on the ECU and, if that doesn't work, consider opening up and separating the boards on the BSI for inspection (or get it bench tested!).

[Sophihall]

Heya just wondering if you had any luck finding the problem? Iam having similar but mine does turn over but just doesn't start.

[napping]

OK - I got the BSI, ECU and key fobs off to a company to run diagnostics on their bench test. They couldn't get the BSI to power up. The BSI is the problem but they couldn't identify which component within the BSI was causing it - so I bought another compatible BSI to have it set up with data from the original. I wasted a lot of time checking wiring etc. due to the intermittent nature of the problem. When I get the BSI, ECU and key fobs back I will refit and report back!

[Gasman14]

Did you get a resolution to this issue?
Very interesting but difficult problem.
Please let us know the outcome.

[Doo]

We had a similar issue with wife's C4 a few years ago. She would park under tree's at work (despite my best efforts of discouraging such behaviour ) .... Anyway, the car was used every day and although it would sometimes play up, such as battery would run down over the weekend requiring a jump start, I didn't get around to fixing the problem until we got back from holiday and the car was being all of the above

I eventually tracked it down to the BSM (under bonnet) which had been inundated with tree detrius, causing damp to stay and created high resistance between every single fuse!

I removed the BSM and used wife's emery board (for nails) to clean each of the portions where the blade of the fuse is engaged. I also cleaned the blade of each fuse as well as the main battery positive connection. Car started, ran, never played up and the same battery is still powering the car several years down the line (although I suspect it isn't as happy as it used to be ).

The fact your car was showing the odd issue, then sat and poof, it's showing the same symptoms as our C4 makes me think condensation has built up in the BSM.

Worth a try

Happy New Year.

[napping]

Did you get a resolution to this issue?
Very interesting but difficult problem.
Please let us know the outcome.

I had a company clone the BSI and bench test with the original ECU and key fobs. I refitted these and now the car at least responds by displaying info and dashboard, but it still won't start! I suspect there was a broken connection within the original BSI as the module was completely dead.

The "new" BSI wakes up as it should. But when I try starting the engine I get nothing. I do get the message that the auto should be in "P" even though the car is manual and the BSI was cloned from the original (which could be read by the cloner). The engine doesn't crank over. I'm not sure what to look at next!