Well this one was a real pig and we had to call in the cavalry several times to try and get it sorted!In the end we tried several replacement ECUs. It started briefly on the first one, and then stopped. Sent it back to Allcar electronics having thought we'd damaged it with say a faulty coil pack, but it was found to have locked out (immobilizer) issue. Tracked the immobilizer down (under the rear seats) and disconnected it. Connected another ECU with the power on this time and it worked fine. Disconnected it and then reconnected it only for it to no longer work.
Note that when these ECUs lock out not even the genuine Pegeuot tool will communicate with them. A colleague of ours who specialises in this sort of work was convinced that he could "unlock it" by probing the relevant wire, which he managed to do, only for it not to start again. He summised that the ECU was at fault again. The third ECU seems to be holding its own, but we are worried that if the power is disconnected again, it will lock out.
The immobiliser has been reconnected (but the pickup coil is still disconnected) so that the remote door locking will work. This is a Siemens unit and according to the local dealer they've had a few problems with these in the past. A new one is £175, so am not sure whether the customer will go with that!
Give the inability to "unlock" these ECUs via scantools, it would seem that we may all need to have to invest in equipment to reflash the ECUs directly!
Cheers
Sean.