Ground dash cluster

[am3rican]

I have a 68 roadrunner. I replaced quite a bit of the dash components in an effort to get the dimmer and tach to work properly. Before I dicked around with the dash - all the gauges would work except the tach and there was no illumination. Now none of the dash gauges work. I think it may be a ground issue because some of the gauges will work spontaneously for a second. I bench tested the tach after I installed a new circuit board and it worked.

How do I check the ground? Need help diagnosing.

This is what I've done so far: replaced all bulbs with LED (still can't get dash to light up), digital voltage regulator, new dash circuit board (I broke several brittle pins when pulling out!old one), new tach circuit board, and sent out dimmer switch for rebuild. Checked continuity on all fuses under the glove box. All other electrical works fine (headlight, signals.

 

[ram250098]

I make it a habit of adding a ground wire to the cluster when I have them out. Clip a wire onto the back of the cluster and ground it..see what happens..if that doesn't solve your problem then the cluster is not getting constant power, you said it works spontaneously...loose contact at board. When you pulled the plug from the old board sometimes the wires inside the plastic connector recess inside and when you push the plug back on it just doesn't make a good enough connection..had this happen once before.

 

[am3rican]

What do you ground the cluster to.and where do you attach the clip on the board

 

[Vermont Rock]

All above comments are good. This probably isn't your problem, but I just bought LED for my dash & they are " polarity sensitive" and was told if they don't work, turn the bulb 180 degrees. But... I think you have a ground problem.

 

[Cranky]

When I replaced all the bulbs in my 66, I went to test them after just laying the cluster back in the hole. I guess I scratched my butt for about 2 hours trying to figure out why everything went nuts and then decided to put the mounting screws back in. After that, everything was fine. The cluster grounds to the metal dash frame that it mounts in....

 

[am3rican]

This may seem like a dumb question,but what are the screw sizes and lengths. Mine didn't match