Breezy_Pete

If the autel thing successfully connected to the engine ECU, vcds probably won't do more.

Check fuse 26 (15 amp).

On mk1 there's a fuse failure, and not the obvious one, which takes out both wipers and washers, I'll try to find the equivalent on early mk2. Wiper relay problem does not affect washers.

Fuse 7 feeds the ignition coils on your car, I've just established, which may or may not help. VCDS lite will indeed work on this car, allowing fault codes to be read from the engine ECU (or any other module) if any are stored.

You have identified pin 16 correctly on the diagnostic socket, by the way. You can see that only 8 of the orifices have contacts in, pin 1 bottom right in your pic - ignition switched 12V pins 4 and 5, leftwards from there, 0V/earths pin 6, CANH pin 7, K line pin 14, CANL pin 15, L line to airbag control unit pin 16, permanent 12V I may watch your video later if I find somewhere with better internet.

Sorry, I didn't make myself completely clear, I think. I wasn't suggesting direct attempts to probe the comms. What I meant was, remove fuse 50, do all the stuff to make the car think it is all closed up, wait at least 30 minutes after, then repeat your mV across fuses measurements. If those that showed activity before now don't, you can probably conclude that in the absence of the radio, everything else shuts down properly.

I believe if the engine ECU doesn't get a valid signal from the crank sensor it will stop enabling the fuel pump relay. Not saying it is that, but it may be one possibility. When attempting and failing to start it, does the rev counter indicate anything? (If it has one). The fuse 7 business seems like it could be a clue; can you share the reg number or VIN to allow me to look up further info. In a rubbish WiFi environment presently though, so can't say when I may be able to investigate.

Is this car new to you, or has it been running OK and now this?

Hello, yes, that's all consistent with needing a repair to driver's side module. I will send you a private message shortly with some options.

Yes, should be always parallel as their sprockets are same size and driven by same chain. Chain has jumped a fair bit. Surprised that the compression test didn't appear to show bent valves. I can't picture how that can be the case.

Message me with the VIN or reg number please.

If you remove fuse 50, then look at what is/isn't fully shutting down in test condition 3, I think you could probably blame the radio itself if everything then goes quiet.

Nice one, sorry for the initial bum steer on fuse location.

Stick a 5 Amp fuse in where that shows number 8, and see if all comes good? Edit: (If you saw the previous version of this reply, please ignore it, I was being daft, rotating things wrongly in my head!)

Yeah, that pretty much rules out a similar problem. I wasn't losing a lot, and there were a couple of other suspect (pipework/joints) spots that I'd blamed 'til I saw that.

Loctite isn't required or specified. Either accept that it probably will be fine, or go elsewhere.

I guess you had a good look down towards waterpump? I did mine on my 1.4/16v Polo over Christmas, just cos it had been ten years since belt kit and waterpump were done last (at VW). Only maybe 50k miles in that time, maybe even less.. Everything was still functionally OK, but the waterpump seal to block had been leaking, for a long time. Worth looking for any similar residue. I had noticed nothing visually from outside the lower cover, surprisingly. Guess it was leaking slowly enough to all evaporate in there.

Bad contact. Put a new one in, and maybe even try to clean the receptacles in the fusebox, somehow.

Swap another one in just in case. Dirty or clean contacts on it?

You need to see whether it has blown or not.

The one I meant looks beige in your previous pic??

Top row of little miniblades, left hand end one, I think. Looks halfway out?

No idea what the busted wire or the device it used to connect to is. Bonnet open/closed switch, maybe? Won't be related to brake light issues, I'm almost certain.

Easy enough to check and replace the fuse, rather than speculate on why/how. 5 Amp miniblade, I think.