Nothing but the speedo

Hi guys,

This forum is great and searching old posts has has helped me out loads in the past, but I can't find anything about my latest problem. Hope someone can help…

I have had an intermittent problem with my 1985 GTI cab since buying it about 18months ago. Basically every once in a while the rev counter, indicator lights, temp gauge, MFA - everything except the speedo - stop working. The first time this happened I thought it must be a fuse or something, but then the next time I started the car it all sprang back to life (for a while). If I turn the ignition and the rev counter etc works I know it will work until I turn off the ignition, similarly if it doesn't work when I switch it on I know it definitely won't work until I have turned it off and on again. This makes me think its not just a dodgy connection, cos surely that would come and go while you were driving?

It seems to happen more when I've been doing lots of short journeys (I spent 6 months doing 100miles a day+ in it and it never happened once), so I was wondering if its something to do with the voltage dropping when the battery is not fully charged. Usually after a good long run it will start working again, but lately it hasn't been working at all, despite a couple of  long runs.

Would a drop in voltage cause the whole thing to fail? I'm a bit of novice when it comes to electrics to be honest, so don;t know if I'm barking up the wrong tree.

Cheers,
Malc.


PS earth lead on the rocker cover is connected

Is it ONLY the instrument panel that stops working? Do all the other electrics continue to work? e.g. wipers, heater blower, lights etc?

If it's just the instruments it could be that the multi plug at the back is loose/dirty or the circuit board is tired.  Also could be a loose earth somewhere on the car.

Keep us updated

HTH

Yep, just the instrument panel.

Seems like it was a bad earth. I found this post on another forum, which describes almost the same problem:

http://www.clubgti.co.uk/forum/showthread.php?t=34325

…so tried connecting the earth lead from the instrument panel multiplug direct to the bulkhead, and it worked! Seems like a bit of a bodge, but it does work, so what the hell eh?

Inicidentally, while I was behind there I found out (I think) why the dash lights dont work - the blue and grey wire coming out of the back of the headlamp switch has completely melted away at some point in the past. Tried reconnecting it, but didn't seem to help. Any ideas?