Defender 90 TD5 Indicator/Fog light issues

Hi All,
Have a 90 TD5 on a W plate. In the space of 1 day from fully working to not working as follows:
1) on side lights (and main) the dash fog light flickers (so does the actual fog light so took out bulb)
2) the dash fog light flicker turns to solid on
3) the dash fog is joined by a left indicator flicker which soon becomes a solid "on" too (not turn flashing)
4) indicators and hazards pack up

Poked around passenger fuses, hazard and fog switches to no avail, any suggestions would be gratefully received! Steve.

Update: got the indicators working again (fuse fiddling) - the fog light remains on when on sides & main plus fog flashes with indicator when lights off and indicating left. No obvious chaffing in steering column wiring - the fog/hazard switches look ok. At least I am mobile.

Sorted. Where the loom comes out of the chassis by the rear cross member the wires were all chaffed and bare - hence shorting. Slight troubles trying to pull enough out to cut and splice but completed ok and all working. What price a rubber grommet v the hassle?

I had a problem with the right indicator causing the rear fog lights to flash. It turned out to be a dirty connection on the plug that goes into the rear lights. I cleaned the centre pin with a nail file, and that was it - works great

my 300tdi has just started going nuts too.

For the last couple of weeks the fog light indicator looked to be glowing slightly. A couple of times the temperature gauge started to creep up a bit too.

Yesterday it truely flipped out:

Temperature gauge redlined within minutes of driving, fog indicator flashing away randomly.

And today everything else joined in:

Turning the heater on caused the dash to go nuts.
Windscreen wipers are no-where near as fast.
Indicators throw a tantrum if you try to use them.
Actual main lights flicker.

I'm leaning to an electical problem here! But why would the engine overheat too (no sign of coolant leak but reservoir is hissing)?

Any clues on where to start looking?