Breezy_Pete

I would say that exonerates the supply and wiring side of it, leaving an oddity with the alternator itself. The extra current available when you connected direct from battery positive probably overcame the problem. Now that you have current meter, see what current you get if you measure that path instead (battery positive to pin where blue wire would go on alternator). I'll just pop out and do the short-to-earth measurement on my Polo as a comparison. Can't remember if I ever did that or reported the result above anywhere?

Depends on the state of the bush(es), I'd say.

Aren't you going to have either firewall or engine in the way of a 32mm open-ended spanner? Sure it's not excessive movement in a wishbone bush?

At that price I would suggest that before ordering anything you check for broken wires in the door bellows, which seems to be incredibly common on the mk2; unless you've already done this?

Item 18, two variants, unheated and heated. Unheated will have no electrical connection, if you aren't sure which you have. LLLParts

Pressure when cold suggests something is being added to the cooling system during running. Combustion gases are the obvious candidate. If there is such a leak, it will get worse, so the next sniff test may be less reassuring. Do the coolant hoses feel very solid if checked at idle after a run where the car is fully up to temperature?

If you can get sufficient access without risk of shorting, try measuring charging voltage right at the alternator; positive probe on output stud, negative probe on alternator body. I'm thinking your 'at idle' numbers for charge voltage are very low (do those numbers rise much if you rev to say 2000rpm?). On a car without start/stop I would expect to see nearer 14.5V unloaded, and not dipping much with the loads mentioned. Testing at the alternator may reveal bad connections/cables if the numbers are much higher there.

NSR window issue is likely to be a broken wire rather than anything more systemic, I think. Look in the front door bellows on that side first, unless both front and rear NS doors get equal use.

Yes that was going to be my suggestion. Precise measurement not needed so any meter at all will do

Do you have a dc current range on your multimeter?

This, I expect; but fitted by fitters, not engineers.

Do yourself a favour @J.R. and add him to your ignore list. 🙂

See image above ^ Unplug connector(s) from it to stop the fan powering up non-stop.

Control module mounted here if you have aircon. It may look slightly different to this image, as there are two versions, other one just has a single electrical connector facing the back of the car.

Does the car have aircon, or not?

Pin 1 at crank sensor connector - yellow/blue wire - comes from engine ECU pin 25 (+5V) Pin 2 at crank sensor connector - yellow/purple wire - comes from engine ECU pin 52 (Signal output) Pin 3 at crank sensor connector - brown/red wire - comes from engine ECU pin 53 (0V) With ignition on, I think you should be able to measure 5V between pins 1 and 3 of the sensor connector. If you do see that, it proves 2 of the wires are intact.

^ I think it was a crank sensor. A Diagnose Dan YouTube video, I think. I'll look up the wiring info this evening if I get a chance.

I'd roll the dice at that ratio I think. Fill it up every time you can squeeze another 5 litres in.

Was the wiring to the crank sensor checked through?

36mm socket for oil filter cap. 6mm hex key for sump plug. 🙂

Behind it under the aluminum cover on that end of the engine. No need to think any more about it. Your odometer is saying 172131km covered. Engine should be OK for quite a few more. EGR valve may be close to end of life if factory original (quite likely not).

^ Auxiliary belt.

How many km has it done?

No; chain.

Have you perhaps had a new battery recently? If so, the voltage may be staying higher, so not triggering a voltage droop cutout on the camera?