Hey all,
coming with a question.
I've P38 Motronic which doesn't want to start.
Battery is brand new, I've changed it because the old one was degraded and I thought it doesn't start because of it.
This Saturday, I've changed cooling fluid and thermostat, run the engine and everything was fine.
This Sunday, I unlocked the car tried to start it and just heard "click" and that's all. No cranking.
I've received yesterday my Nanocom Evolution and just used it for a first time. BeCM says no errors.
On "contact" I'm trying to look for info from the "Faults" of "Motronic", but it gives me error that cannot connect to ECU.

I've looked over RAVE and I should be checking circuit breaker 1 and 5 in the fuse box in the engine. Didn't do that, still, will do it after a couple of hours, as still being on work.
Is that the only possible issue?

P.S.
Just remembered that before changing the thermostat, I've towed the car, without the key being on position 1 and without having a fuse in position 11. But I've changed the thermostat after towing and I've started the engine and got it warmed up (for air bleeding of the coolant system), so this should not be an issue, but just to mention it.

Are there any other possible reasons for this to happen?

You've got 3 sources of a click. There's a very light click from a relay dropping out in the BeCM (so that will be a click from under the seat), there's a click from the starter motor relay (relay 16) in the underbonnet fusebox and there should be a louder click from the starter solenoid. Fuse 40 supplies the starter relay and the EAS compressor. If the starter solenoid is pulling in but the starter doesn't turn, then it is new starter time.

As for towing without a fuse in 11, how far did you tow it? It won't affect starting but the gearbox won't have liked it as it will have been turning but without the pump running so it will have no lubrication.

Hey Gilbertd,
thanks a lot for the detailed reply, as always.
I'll be looking through these steps, but for now it might be an issue with the positive cable going to the starter.
I've been pushing them up and down and the car started. Then it didn't want again. Didn't had the time to test it for a third time, but will do it tomorrow.

Regarding the towing, somewhere around 3.6km with slow towing, no more than 30km/h even slower. I suppose that would not impact the gearbox so much.
I was wondering for the reason to be putting fuses here and there, now I got it.

When you put a fuse in position 11, it puts the transfer case into neutral so while being towed, only the transfer case is turning, not the gearbox. The gearbox oil pump is immediately behind the torque converter so is turned all the time the engine is running. So with the engine not running but the car moving, it has no lubrication.

Hey Gilbertd, thanks for the detailed explanation. It is much appreciated.

The issue appears to be a smaller wire (Lucar connector) coming from the BeCM relay, triggered by the ignition switch, i.e. the solenoid feed wire. I've moved that one a bit, it was sitting "unnatural", and now it starts. Made a test drive with bumps, etc. and starts again. If that is the case, apparently while changing the thermostat I've unknowingly pulled the wire and made the issue myself.

Sharing the issue here for someone like stumbling on that issues some day :)