Help! Tach Problems!

[sandman126]

I have a 1986 GLI 8V and I cannot get my dam tach to work. The only time it works is when it's pretty cold, but as soon as the car starts warming up it stops working again. That means i have a short somewhere right? If anybody has any info on this it would be greatly appreciatted!

Mean time i'm gonna eat this cookie!

[fatmobile]

I've taken these apart and changed resistors/caps to get it to work with a W terminal on the alternator,.. for stock-looking diesel tachs.
Only thing I can think of that would change with temp might be a bad solder joint, cold might shrink it back together.
Pull it out and touch a soldering iron to the joints,.. a magnifying glass might find the crack. It doesn't need to be a big crack in the solder, usually very hard to see with the naked eye.

[sandman126]

Thanks, i'll have to look to see what i can find.