bad connection near ECU

[craqck pot]

Hi there
I have a Citroen Picasso xsara 08
From time to time I have turned the key to start the engine and the starter motor clicks then there is a complete loss of power everywhere.

In the top right hand corner of the engine bay there is the fuses box; then next to that there is a strange looking plastic box that bolts to the gear box. On that strange plastic box to the right of it the ECU is located with several unknown electrical devices. On the other side of the box there is a wiring clamp where 2 big black wires join on a wire crimp terminal and a thinish black wire too that goes off to the ECU and other unknown electrical devices. I have unscrewed the thinish black wire and wiggled it around and I hear clicking noises coming from the ECU and other unknown devices, then I screw it back on and that seams to do the trick!

But I have examined the wire and it is clean and unbroken so I don't know why this bad connection is happening

[xantia_v6]

The symptoms you describe are classic of a dirty battery terminal or a battery cable with a failed connector joint, or a battery with a failed internal weld.

You really need to get a volt meter and when everything is blacked out, measure the voltages around the main feed to see where the power is disappearing.

[white exec]

Second that. If the car has the original PSA lead (Pb) lump battery connectors, it's worth replacing them with new brass ones.

The originals deteriorate internally over the years, and lose their grip on the stranded cable, making a poor connection. If either battery terminal gets at all warm after trying to crank, that is a giveaway for a poor connection there.

[lcwin]

Try to start car by putting ignition switch to ON and use a wire to activate the starter solenoid. Its probably the ignition Switch contacts oxidized

[craqck pot]

Second that. If the car has the original PSA lead (Pb) lump battery connectors, it's worth replacing them with new brass ones.

The battery is under the passengers seat with clamp type terminals

[craqck pot]

Try to start car by putting ignition switch to ON and use a wire to activate the starter solenoid. Its probably the ignition Switch contacts oxidized

But the problem is in the engne bay not the ignition switch

[lcwin]

PSA group cars have low quality electrical connectors and joints. Since you think its the blk wire then clean with contact cleaner and fine sandpaper at the point of contact and connect back the battery .
Your starting issue is usually due to what I describe earlier.

[craqck pot]

so what are you saying; I should jump the solinoid on the starter motor to see if it turns or not?

[Hell Razor5543]

On the earlier Xantias there was a design problem whereby the ignition switch would, over time, burn out because Citroen was putting too high an amperage through it to trigger the solenoid on the starter motor. A common fix (which, I believe, Citroen adopted for the later series Xantia) was to fit a heavy duty relay into the circuit. The ignition key closed the circuit for the relay, which in turn then closed the circuit for the starter motor solenoid and this would then spin up the starter motor.

[xantia_v6]

I think that the car in this case already has a starter solenoid relay in the BSM, which is controlled by the engine ECU, not directly by the ignition switch, so adding an extra relay is not going to help.

What is needed is diagnosis by reading any fault codes, although they are unlikely to be definitive in this case, and/or measuring the voltages around the BSM.

[RichardW]

Can you post a pic of what you are talking about? I think that is the +ve post on this car where the wire from the battery connects onto the +ves in the engine bay?

[lcwin]

so what are you saying; I should jump the solinoid on the starter motor to see if it turns or not?

When you encounter the problem of not starting , turn the key to ON and use a jumper wire from positve battery to starter solenoid and see if it starts. Thats all it takes to verify if the contacts in the start key is having problem.

[lcwin]

And yes it also can be due to the starting relay as mention by xantia v6.

[xantia_v6]

The first post says that the failure leads to a complete loss of power everywhere, so the fault is not in the starter control circuit or relay, it is in a high current supply circuit, or around one of the fuse boxes. It needs diagnosing with a voltmeter.

[craqck pot]

On the earlier Xantias there was a design problem whereby the ignition switch would, over time, burn out because Citroen was putting too high an amperage through it to trigger the solenoid on the starter motor. A common fix (which, I believe, Citroen adopted for the later series Xantia) was to fit a heavy duty relay into the circuit. The ignition key closed the circuit for the relay, which in turn then closed the circuit for the starter motor solenoid and this would then spin up the starter motor.

Mine is an 08 modal. do you think this is one of the earler ones in question or not?