overheating or electrical problem???

[tattoodrob]

hello,i have recently noticed that my car shows it is running hotter when the lights r on than with them off!!it looks like temp is creeping towards 100 then i turn lights off and it immediatly returns to 90.anyone else had this b4,i presume i have an electrical fault somewhere.....i dont think il worry about it but if any 1 else has any ideas....i aint taking it to garage just for this.ta rob

[jonnyb]

Sounds electrical. Bad earth in the instrumentation. check the otter switch and the fans come on at the correct temp, and get it fixed when it starts to annoy you too much!

[chimburt]

agreed!
don't panic

[V8 Archie]

Agreed. Almost certainly an earth problem. If the lights are involved it could be the earth point immediately behind the offside fan (have fun getting at that one to clean it up) or the one in front of the driver's footwell between the wishbone and steering UJ (get under the car to access this one).

Alternatively, it being apparently instrumentation it could be one of the internal ones (either side of the transmission tunnel roughly where your left knee is when driving and the same place on the other side).