Today was electrical shenanigans, which I want to sort before taking everything else apart.
It won't start on the key so I started with that - turns out the F125 is not sending the P/N signal to the interlock relay. That's easily bypassed for now using the same solution as for the manual swaps:
Based on Andrew's investigations, this should be the upper pair of the four large contacts in the F125 so I will sort that when I get underneath. I'm still undecided on whether the engine is coming out of this one.
So, now it'll spin over on the key but won't start. Attempring to start lights up almost every error light on the dash and the TCU instantly goes in to limp mode with canbus errors in the TCU, cluster and ESP. Interestingly, during this the ECU is quite happy to talk to VCDS, but isn't powering up anything on the engine.
There is a loose connection or broken wire in here somewhere
I started off checking canbus connectivity - that's all good, so it must be a power supply problem. The ECU has a number of supplies - switched ignition (T15), permanent live (T30), and a switched live from the main ECU relay.
The start-up sequence is normally T15 from the ignition, then the ECU powers up the main relay (from which it has a feeback wire) then, if it doesn't immediately see an rpm signal from the crank sensor, it will do a self-test on the throttle body.
I started with T30 - all good there, 12V live. Then T15 - switch on the ignition and all good there too. So ECU relay then? No - that powers up fine, switches on the coils and injectors. Odd
So I turned the key and it started! Poking it yesterday broke it, and poking it more today fixed it, so while it was running I went round poking it some more
I touched the main ECU fuse on the T30 supply and it shut down instantly. On investigation it turns out that the water ingress in the electronics box has caused corrosion on all of the fuse holder contacts and the fuse terminals. It seems that with switched ignition only, and not its permanent live, the ECU can power up enough for diagnostics but not enough to run. Motronic ME7 has a 'boot mode' which allows it to be bench-tested and flashed without throwing error codes. I suspect it was in a similar state to boot mode in this case.
With that sussed I cleaned up all the terminals and replaced and the fuses and now it fires up on the key, and stays running while poked
Success! Someone has clearly been tinkering in there before and this is very likely why it was parked up.
Looking at the heater valve block, it is clear that the perpetrator of the electronics box mangling did so in order to hack at the valve block. There are at least six things wrong in this picture
1, the air intake servo cover screws are missing
2, the valve block is a PF / FL1 unit with the wrong connector
3, the valve block is hanging off the hoses as said perpetrator hasn't attached it to the bracket
4, the FL2 connector has been cut off and replaced with spade terminals
5, the recirc servo wire is routed incorrectly
6, the hoses aren't even attached properly
With that all fixed properly I moved on to cleaning up in preparation for Botang's hole and replacing the electronics box.
As expected there was a load of leaf matter under the heater, which was relatively easy to get out with the electronics box removed.
Cleaned up:
Botang's hole - as usual the tape just fell off while cleaning up.
I did the usual fix of filling the hole with a plastic rivet and then covering it up with seam sealer.
Some things crossed off the whiteboard already
The folding mirrrors weren't, which was the module - that's first to get dripped on by Botang's hole so that was an easy fix.
I'll put the electronics box back in tomorrow and I want to see how it starts, having been run again today. The lifter tick was much better today but I couldn't get a good feel for chain tensioner noise as I'd had it spinning on the starter while testing so it already had oil pressure. If it rattles tomorrow the engine will be coming out. If it doesn't, then it won't