today i noticed my tach gauge flaking out, I had the signal on and it started to bounce to the beat of the signal then it started to just drop for no reason. whatever rpm it was at it would drop to the bottom then come back then drop again. Its not real important for me to have a tach but it is nice to have working gauges. Anyone ever experience this or have any idea what the problem could be?

 

My guess is that it is a ground problem, now if it is in the gauge wiring or some were else I don't know. The ground for the signals is "backing up into the tach" which means the signal ground is some how passing through the tach, and this open ground is causing it to bounce when ever it is making contact or losing contact. This will most likely require some involved wire chasing so good luck.

400m
85' bronco II
86' f-150(400 w/ edelbrock power pack. 6" lift, 4 speed)