Breezy_Pete

Nooooooooooooo. Why? If it's just about other commitments, no worries. Talk to me about it tomorrow, please. 🙂

One more question to ponder; how dry versus leaky would you rate the cabin of your car, and how long have you owned it for? I think I've come across a similar problem in a car that had condensation corrosion on some of the relevant pins of the connectors to this module, known in wiring diagrams as the Onboard Supply Control Module, and in VCDS as Central Electronics.

That sounds like you've chosen the most appropriate one. I'm not saying that it is the problem, but from what I skim-read above, I think the other one, above clutch pedal, probably isn't involved as it does Central Locking of all doors except the tailgate, and I think you've described all of those as working OK. Have you looked for wire breakages in any of the door bellows? Or signs of water ingress and corrosion of connector contacts?

What is the part number of the module you've bought? There are two modules that are often confused. One deals with central locking and alarm, the other does lots of other things. You've done a great job of investigating the behaviours and describing your findings, but I think it's too late in the day for me to focus enough to interpret them. Will revisit tomorrow.

You may also need to clean up the connections of the high current connections in the charging circuit. The earth wire from chassis leg to mounting bolt of starter motor (the main engine earth) would be my first suggestion for improving alternator voltage numbers.

I think that confirms the breakage of the DFM wire between alternator and engine ECU.

What does the last measuring block value in 53 read, after the voltage? May be labelled "Generator load".

There was a thread very recently where a blocked precat was giving weird symptoms on a 1.4/16V. Might be worth a torch-facilitated look through the hole that the precat lambda sensor goes in? What is the MAP sensor pressure reading at idle with cold and fully warm engine? (Happy to compare with ours)

Very disappointed for you Ryan, but you should've listened to uncle Pete and looked to see if the old one was giving odd readings before that throw of parts darts.

Keep (in the car) at least one of the working ones you swap out, just in case one of the new ones let you down. 🙂 Did you check spark plug of cylinder 1?

Try removing and cleaning up the main electrical connections.

Pull upon the little cubby that's near your right knee when you're sitting in the driver's seat. Then pull it a bit harder and it opens further to reveal the diagnostic socket. 🙂

Use VW 502 00 spec and change it every 8 months. 😁

Also worth checking that the relevant fuses don't have corroded contacts or loose sockets in the fusebox.

No worries pal. The C/L versions have an 8-pin conn seen near the 2 in your second pic.

I have the vaguest of memories that the door open switch might be of the more traditional plunger-switch in hinge area on the non-C/L cars. The locks certainly look different, I think this is the latest revision for rhd drivers door: https://www.stevensvwspares.com/vw-lupo-door-lock-mechanism/drivers-side-front-door-lock-catch-manual Struggling to find 360-degree views of one, on phone. @varooom, can you perhaps do better? I seem to think this came up before and the conclusion was either that there are no electrical connections to these manual locks, or just a two-way. Can't remember which, but can't see one in that StevensVW pic.

The other problem with autodoc and all of its sister companies that pretend to be local by having .co.uk web addresses is returns. The parts tend to come from Berlin, or somewhere in Poland I think, so returning items will be a PITA. Use TPS if at all possible.

Great result and thanks for letting us know what fixed it. 🙂

My bad, sorry. Wouldn't worry about either to be honest, see if they fail next year, then do something.

That's referring to the rear bush of the front wishbone, both sides. Post the fail code number for confirmation.

extremely unlikely

The door lock fault can be the solder joints where the connector attaches to the circuit board in the lock also, as well as the microswitch. 20200910_155143 - Copy.mp4

Door problem will be the lock, I think. J519 has nothing to do with lambda sensors. I will post a circuit diagram of the lambda wiring for you tomorrow.

It's defeating my brain at the moment, sorry. You could measure the resistance of the heater on each sensor, I guess, in case both have burnt out 🔥?

The fuse supplies one side of the heater in each sensor, the other wire of each heater, and the two main sensing wires from each all go to the engine ECU.