Breezy_Pete

It's actually more about keeping it cooler in proximity to a hot engine.

Did you check the bulb on nearside? And offside, come to that.

I guess so. I'm not very familiar with it. If you download the 2004 circuits from the link I gave above, and search the pdf for "bulb failure" you should find the relevant pages. I vaguely remember taking one of those 'relays' apart many years ago, and finding that it was just a set of current shunts monitoring the feed current to each of the bulbs.

Does your car have bulb failure warning system?

I think the only thing between fuses and bulb connectors is the connector pairs where the engine bay loom meets cabin loom at the firewall. BCM still not involved!

I've had emails about erWin Audi and erWin Seat going the same way, can't be long before VW and Skoda send me theirs.

Does your car have halogen or HID (Xenon) headlamps? If halogen, there's just the rotary light switch, and fuses. If xenon, there's also a starter unit after each fuse (near light clusters I think).

Link to manuals (including wiring diagrams) https://www.briskoda.net/forums/files/file/76-mk1-fabia-workshop-manuals/

Oh, that is a shame. ☹️ There's time to download quite a bit between now and a month's time though.

I wonder if this is just for UK users, or more widespread?

BCM controls indicators via a solid state chip containing FETs. It doesn't control headlights at all, I believe. Circuit scrutiny not far off now, or you can research yourself via handy link to mk1 workshop manuals that can be found on here.

No, that's the indicators, not headlights.

I don't think the BCM powers the headlights. Will have a look at circuits later. I have pinouts for BCM somewhere, but doubt they'll be relevant.

Will be variable, depending on ambient temps, airflow through rad due to motion, etc. I don't think VCDS can help you here, no. At this time of year in UK, with a 1.9 diesel engine, I doubt you'd see fan action due to just radiator temperature very often, if ever. Why the concern?

Coolant temperature of 95C at engine won't be hot enough to trigger fan action via the radiator thermoswitch. The thermoswitch is generally near the outlet of the radiator, so coolant reaching it has already cooled due to passage through the radiator. The thermoswitch threshold for low speed activity of fans is 95 approx. But that's temperature at the thermoswitch, not at engine (where the sensor you're interrogating lives).

Dashboard gauges are 'frigged' to display a reassuring temperature over a range of real temperatures. Feature not fault.

First of those is the VAG part number, other is Bosch part number.

Fair enough, it was a good point Aldfort raised though, new cars with different fuel from old ones presents a risk. Easier to misfuel petrol into a diesel than t'other way round though, due to different nozzle diameter.

Oh yeah, wonder if it was petrol though.

Any refuelling occur?

Tempting to imagine that this problem was why the previous owner offloaded it. Might indicate potential for a frustrating time if retained.

Since some of the lock module signals connect to/through the window motor module, and could be corrupted by faults within that, see what happens if you unplug the window motor. If lock activity calms down, consider acquiring and test-fitting a replacement window motor module. I have a suitable item available, let me know if you might like it to try.

Extremely common. Good practice to take off the battery negative clamp before such work, yes.

Check for broken wires inside the bellows at the A-pillar.

I think a manual 1.4/16v will have an 02T family box. From memory it's a 13mm nut that holds the change lever down on its splined post. (May be bigger, memory not really trustworthy). It only fits in one orientation too, again from memory, so need need to mark alignment.