Xsara Picasso starter problems

[TitusGroan]

This is a 1.6HDI with a starter problem. Sometimes the starter will not run. It's usually OK cold, less so when hot. If it fails to start it will bump-start. I can hear the starter solenoid ticking when it fails to start. So I checked out the procedure for replacing the starter... yikes, almost engine out!

So I wondered if it was actually the solenoid... I ran a lead to the starter side of the solenoid, back to a small bulb. When the starter runs OK the bulb lights. Not when the starter fails to run. So I assumed that the solenoid, even though it was actuating (ticking, once each try) did not make a good - or any - contact.

So I thought I'd parallel up another starter solenoid. I ran battery +ve in 100A cable to the new solenoid near the plastic 'tower of power', then from the solenoid down to the starter side of the existing solenoid. I ran a lead up from the 'activate' terminal on the solenoid up to the new solenoid. You can see how it's set up, a simple parallel solenoid.

But it doesn't work because when the hey is turned and the engine starts, the new relay stays ON and the starter keeps running. This is because the 'activate' terminal is staying high, which activates the new solenoid.

It seems that some control system is sensing the load of the new solenoid coil and holding the 'activate' line high. Any idea what's going on? If I can't solve it easily I plan to use the new solnoid as a backup, wired to a button in the car, press to start when the normal one just 'ticks' and won't work. Is that a reasonable alternative? I really don't want to have to replace the entire starter/solenoid assy.

[RichardW]

It's probably some weird back flow effect whereby the starter current is back feeding the new solenoid.

The starter failing to operate in this way is common this engine - no idea why that should be. It is well buried, and a PITA to change (I had the same on my 307, but never managed to get it changed, I was beaten by the 3rd bolt over the top of the starter) - however, in the long run it really is going to be easier.... Mine never failed to start eventually, sometimes it took 4 or 5 tries!