Odd C5 electrical fault

[michael maurice]

Hi

I have a very odd fault with a C5 estate 52 reg 2L diesel.

Every time I unlock the doors, open a door or switch the engine on, the rear wiper starts. It stops after a few seconds.

Everything else works ok and it isn't serious, just puzzling.

Can anyone offer a clue as to whats causing this mysterious fault?

[Citroenmad]

My guess would be a comms 2000 fault.

[cachaciero]

, wiper motor, wiring, BSI, COM2000 would be my order of suspicion. There have been a few electrical type problems around the rear window of the estates to do with glass locking and I wonder if some one has done something not quite right such that there is x talk between the wiper motor and door lock wiring.

cachaciero

[michael maurice]

Thank you both for your replies.

Is the fault dangerous or could it lead to further complications?

What is BI and COM2000?

Thanks

Michael

[spider]

Com2K is the indicator / wiper switch assembly. The do fail more often than people would like although to be fair they are a lot better than the first (year 2000 ish) few ones when they switched to muliplexing, they will have all been changed a few times though.

BSI= Built in systems interface, again this is a 'box o tricks' for want of another word that effectively controls most of the electronics. Instead of say having an indicator switch to flasher unit then to bulb it goes from switch to BSI which then deals with the signal received and operates the indicators and / or anything else electrical that should be enabled.

[cachaciero]

Com2K is the indicator / wiper switch assembly. The do fail more often than people would like although to be fair they are a lot better than the first (year 2000 ish) few ones when they switched to muliplexing, they will have all been changed a few times though.

With respect that is a rather sweeping statement.
Yes there have been published failures of COM2000 units but from what I read in various places I would wager that the average 10yr old C5 still has it's original fit COM2000 unit.
From inception there were basically two kinds of COM2000 unit fitted, multiplexed i.e with a CANBUS interface and those without, generally only low spec cars without auto-box or ESP would have had the non can unit fitted, any car with either Autobox or ESP needs the CANBUS version.
To try and put the as published failure into some kind of perspective, it seems to me that of the two, the non multiplexed seems to have the most reported failures but on any of the Forums that touch on these cars there will be far more reports of MAF failures than that of COM2000 units.
FWIW my 2001 C5 still has it's original COM2000 unit as far as I can tell from the service history that came with the car which does seem to be quite comprehensive.

cachaciero