Very strange car fault - Citroen C2 - fuse box? BSI? BSM? Please help

[agi1190]

Battery seems to be working fine, there are no issues with starting, when the car is not faulty, and both mechanics I went to with the problem, as well as the AA recovery guy, said that the battery is fine and there is no evident problem with that. I've had a few attempts of resetting, disconnecting and reconnecting various things, with no result (even found a method for resetting BSI module, but no success). While I aim for a miracle to happen, with little idea what I'm doing, nothing helped so far.

 

[static zap]

Do you have any blinking security active light at rest , to compare two conditions (good.bad) ?
When dark enough to see !

 

[Ziggie]

Checking the wiring diagram would possibly help with the puzzle... I guess?

The whole fuse box was replaced recently, which only "worked" for a couple of days. I'll let you guys know once (if) I get my car started and bring it to the mechanic. I'll have a longer chat with the guy once I'm there and see if he has any ideas.

Good luck . Let’s know the answer!

 

[ruston]

As @Ziggie . A bad earth could cause those problems too, but as @DPG you would think this would have been checked by the qualified people that have already examined it .
However ensure the negative battery connection is sound and connect a jump lead between that and a good connection to the engine block to see if that eradicates some of the symptoms.

 

[DPG]

As @Ziggie . A bad earth could cause those problems too, but @DPG you would think this would have been checked by the qualified people that have already examined it .
However ensure the negative battery connection is sound and connect a jump lead between that and a good connection to the engine block to see if that eradicates some of the symptoms.

I agree, if they haven't checked battery, grounding, fusebox supply etc then you need to take it somewhere else. This needs someone who is experienced in diagnostics.

The earthing lead suggestion above is worth trying though, and nice and easy to do.

 

[static zap]

My first step would be with a cheap voltmeter ,to check nothing strange going on with battery volts and a lightly used car.
..can also look for volts on things earthed -allegedly- ..

 

[ruston]

Have you checked the MOT history to see what any past failures were. Has it it suffered any collision damage or advisories on corrosion observations. Some failures may give you a clue to a progressive fault.

 

[stanwelbach]

Could be a number of things which I will expand on later but first can I ask that when the car is faulty, do the headlights work at full brightness? If so this rules out a bad battery and parasitic draw (as the battery would go flat on a regular basis)
Is the starter motor and its circuit in working order(has this been confirmed by the auto electrician)?
Please report back for part 2.
.

 

[agi1190]

The car decided to start today after 3 days(!), took it straight to the mechanic. Told him some of your ideas guys, it might take days to get it sorted though. I will keep you updated.
After turning the car off, the fault came back on soon as it was locked, so mechanic saw it as well. We'll see, fingers crossed. Soon as this is sorted I'm probably going to sell it as I honestly can't trust this machine anymore.

 

[agi1190]

Could be a number of things which I will expand on later but first can I ask that when the car is faulty, do the headlights work at full brightness? If so this rules out a bad battery and parasitic draw (as the battery would go flat on a regular basis)
Is the starter motor and its circuit in working order(has this been confirmed by the auto electrician)?
Please report back for part 2.
.

When the car is faulty, there are no lights whatsoever, it's not a battery or alternator, had that checked already.

 

[DPG]

The car decided to start today after 3 days(!), took it straight to the mechanic. Told him some of your ideas guys, it might take days to get it sorted though. I will keep you updated.
After turning the car off, the fault came back on soon as it was locked, so mechanic saw it as well. We'll see, fingers crossed. Soon as this is sorted I'm probably going to sell it as I honestly can't trust this machine anymore.

Tell whoever buys it though. Don't drop the problem on to someone else.

 

[agi1190]

I'm aiming to fix the problem, which probably will cost a bit, then probably part exchange for another vehicle.

 

[stanwelbach]

When the car is faulty, there are no lights whatsoever, it's not a battery or alternator, had that checked already.

Get your mechanic/auto electrician to check the fusible link that's attached to the +ve terminal, these can become oxidized over time.

 

[ray2frost@btin]

Haha speaking of which, I tried to register to a Citroen forum, but they seem to be having a server error, how ironic...

Which fuse box was replaced? check middle plug in under bonnet fuse box(pics attached

 

[agi1190]

Car is at mechanics now, can't check it myself at the moment. I hope he'll find out what's wrong in there.
The fuse box he replaced before was the engine bay one, which did not help in the end.

 

[stanwelbach]

If it was with me I'd be checking:
Powers and grounds (Battery, starter relay, solenoid, starter motor etc, ect.)
Scan for codes, (dtc's) and perform a health check) check to see if all modules are communicating with each other.
Check CanBus resistance (should be approx. 60 ohms across pins 6 and 14 on DLC or at any control module)
Check CanBus signal and voltages, CanH and CanL with a scope.
Throttle body acuator and sensor (power and ground)

 

[DPG]

If it was with me I'd be checking:
Powers and grounds (Battery, starter relay, solenoid, starter motor etc, ect.)
Scan for codes, (dtc's) and perform a health check) check to see if all modules are communicating with each other.
Check CanBus resistance (should be approx. 60 ohms across pins 6 and 14 on DLC or at any control module)
Check CanBus signal and voltages, CanH and CanL with a scope.
Throttle body acuator and sensor (power and ground)

Must admit I'm assuming they have already checked for current or historic fat codes, but we don't know.

OP - is the garage experienced with this sort of fault finding?

 

[stanwelbach]

Must admit I'm assuming they have already checked for current or historic fat codes, but we don't know.

OP - is the garage experienced with this sort of fault finding?

You never know, not all mechanics can fault find, a lot just throw parts at it in the hope it fixes it.

 

[agi1190]

I've never used the services of this car electrician before, didn't really need it to be honest. After the first failed repair attempt, my "usual" mechanic wanted to send the BSI module away for repairs (around £200+) which is not a guarantee to fix this problem. The car electrician guy I left my car with today seems fairly genuine. He did diagnostics of the car free of charge, found the fuse box second-hand online (as he was not certain whether it would help or not, diagnostics were not clear, and apparently, there are no faults shown when the car is running, on the other side, when it's faulty he could not get a response from the system) and charged me only for the part and an hour of labour.

My "usual" mechanic charged me £70 for diagnostics and fiddling with the cables (he literally said that), which resulted in my car starting, but then the fault came back the very same day. And they were very blunt in saying that they have no idea what's wrong and it will probably cost hundreds to get it sorted. I got also a feeling that they could not be bothered with this either, rather focus on people's clutches or brakes, hence throwing the large bills in the conversation to put me off.

 

[Ziggie]

One of the techniques for finding problems is to disturb the cables. This checks for poor connections . Given you documented this above , it becomes likely that there is a bad connection either in the positive or negative wiring . It is also possible that this is temperature related.

in older times, I had a car that would start and fail when driven a few feet. Wait 5 minutes and it started again. Fault was a loose connection which broke with the vibration and settled back when stationary.

let’s hope it’s a bad connection and it fixes very easily. Tampering with the wires is a recognised technical method