Hi all. Not sure if I've mentioned this before, but my Laser's developed an annoying elecy prob which is proving a real pain to sort. To cut a very long bore as short as poss, the car is fine (in all respects) until I flick the headlight switch on. Then immediately the fuel gauge goes over the top, and... (but only after the car is up to normal temp) the temp gauge goes similar! Also, the dash illumination bulbs (x6) don't work. They all failed at once, so it must be a circuit thing. As all this only applies when headlamps are switched on, I'm convinced it's a lighting circuit fault, and have checked the following;

Voltage reg swapped for brand new item, but as only a prob with h/lights 'on', I'm presuming this is ok.

Have swapped the highlight stalk over with one that works fine on my other motor, but still get same resulting fault.

Have checked lighting earths, ie: attached to headlamp relay under pass side of bonnet, rear lamp assembly earths (the screws that hold these assemblies in place).

The steering colomn earth that attaches to the headlamp stalk assembly seems ok.

There is also an earh behind the plastic footwell trim (drivers side). This looks to be a good as the day the car was built!

The instrument cluster circuit board all looks fine, no obvious signs of burning or damage (although when this first became apparent, there was a momentary wiff of elec burning, but nothing looked wrong. I was driving in daylight, headlights off).

The multi plug that goes into the rear of the instrument cluster has been checked for unusual elecy readings, but all terminals seem to be ok (nothing obviously wrong!)

All fuses (main fuse box and h/lamp relay) seem ok, besides there are no other singular faults that indicate a fuse problem, by this I refer to the dash illumination prob....the rear number plate lights are on the same fuse, but these are working fine.

Any thoughts welcome, as I'm loathe to drive it with lights on (at night) in case something overloads the elecs, and makes the problem twice as bad!

Cheers

PS; headlamp bowl earths seem ok also!

Hi Al
Not great with electrics but as you have checked all the possible earth points this would only leave the temp and fuel sender connections.
That then only leads you back the where all the live parts of the different circuits are close to each other so I think I would suspect the circuit board on the back of the instrument cluster if you have a spare cluster that you can
connect up it would at least eliminate it as a possible cause.
Do the headlights light up?