Instrument cluster grounding

golfprorich · Feb 9, 2015

Had the instrument cluster out to replace a couple bulbs and to see why the rev counter is intermittent.

I cleaned up everything best I could and re-installed the cluster. The rev counter worked from start up which it never has done before. It usually works after the car has been running for 10 mins or so or I go over a decent bump in the road.

It then became intermittent again but a few vigorous presses of the trip reset button got it going again. However if I press the trip reset button several times in quick succession the volt meter needle jumps up and down.

Is there any way of re - earthing the cluster as I think a bad earth is the issue?

bmnelsc · Feb 10, 2015

Not sure if you did this already but I read (in Panorama - tech question about fuel gauge readings actually) that one step in clearing instrument cluster problems was to go over all the copper circuits on the electronics board with a pencil eraser to clean off oxidization - I'm guessing this includes special attention around all the contacts. With this side clean and the earth contact for the cluster cleaned maybe this will solve the problem - can't hurt anyway.

golfprorich · Feb 10, 2015

ORIGINAL: bmnelsc

Not sure if you did this already but I read (in Panorama - tech question about fuel gauge readings actually) that one step in clearing instrument cluster problems was to go over all the copper circuits on the electronics board with a pencil eraser to clean off oxidization - I'm guessing this includes special attention around all the contacts. With this side clean and the earth contact for the cluster cleaned maybe this will solve the problem - can't hurt anyway.

Thanks, not heard of this and as it only takes a few mins to get the cluster out its worth a try!

Can you describe exactly where the cluster earth is?

tref · Feb 11, 2015

I seem to recall something on here about cleaning up the voltage stabiliser contacts making a big difference to instrument performance, might be worth doing a search on here for that.

bmnelsc · Feb 11, 2015

Sorry - haven't done this myself (yet) but I believe the ground points are identified on the current flow diagram along with a brief description of their location. Perhaps someone else can point it out. I'd be looking for a stud on the firewall not too far away - probably center or left of center toward the fuse box.

zcacogp · Feb 11, 2015

Poor grounds in the instrument wiring loom were a common problem on Mk1 Golfs and led to numerous instrument problems. It was much easier to make a new ground for the loom than faff around finding the dicky one. Find the earth wire in the loom and splice a new wire into it, and make a new ground somewhere on a bracket somewhere by drilling a small hole and scratching the paint off around it. Put a small self-tap screw into the hole and wrap the end of the new wire around it (or put a round connector on the end of the wire). Do the screw up tight and bob's your uncle.

Oli.

golfprorich · Feb 11, 2015

ORIGINAL: zcacogp

Poor grounds in the instrument wiring loom were a common problem on Mk1 Golfs and led to numerous instrument problems. It was much easier to make a new ground for the loom than faff around finding the dicky one. Find the earth wire in the loom and splice a new wire into it, and make a new ground somewhere on a bracket somewhere by drilling a small hole and scratching the paint off around it. Put a small self-tap screw into the hole and wrap the end of the new wire around it (or put a round connector on the end of the wire). Do the screw up tight and bob's your uncle.

Oli.

I think I will take this route. Today the rev counter behaved, went off once after hitting a bump but otherwise was ok [:'(]