Headlights on = dashboard dead

Hi,

I have an interesting little electrical problem that I could do with some help solving.

In my 1983 Gti tintop when I turn the headlight switch to the on position the power to my dashboard instruments dies, no lights, no gauges and no revcounter.

I have tried with a spare headlight switch, but this has not solved the problem. I guess there is a bad earth or an open circuit somewhere.

If anyone could give me a hint how to solve the problem it would be appreciated. I have a multimeter and have been poking around but cant seem to find the problem.

Thanks

Ash

The only thing I can think, is that there's a missing or bad earth. I figure, when the dashboard lights go on, it raises the dashboard's earth point, so far that it stops the other instruments. I am amazed the speedo stops working too, since this is mechanical! And also, why are the dashboard lights on with the lights off? That doesn't make sense either!

Hi,

Sorry my post wasn't entirely clear. Anyway the solution if your dash lights are not working when you switch your headlight switch to the on position is a bad earth that is connected to the cylinder block. Reattach that earth and it should sort out the problem.

Cheers

Ash

i had this fault to when i done a engine swop on my last one, had me scratching my head for a bit, after removing the dash clocks and switchs checking earths etc i noticed that a engine earth wasnt connected evernually. strange

there is a earth on the plug for your clocks, its the second wire in, earth it to the body that should work

I've got the exact same problem which started two weeks ago, turn the lights on and the dash revs etc die, the only dash illumination that still work are three clocks by the gear stick.  I cant comment on the speedo, as my cable is not connected, due to the clip that holds it in snapped, I shall go shove my head under the bonnet tomorrow and check the little wire  :wink: .

easy way to check it is to get some jump leads and connect them from the batt onto a good clean bit of metal to act as an earth and try it.
if it works then you know its earthing.

ps. check the gearbox earth too.