You didn't say what it's doing so we have to guess at a cure. If it intermittently stays on zero, listen to Jacobandnickolas, plus, check for intermittent connections on the circuit board that runs the tach. It's snapped onto the back of the instrument cluster. Connection problems on the circuit board CAN cause the pointer to stay at something higher than zero, the same as when you turn off the ignition switch.
If you find that the pointer sticks in certain positions, typically around 2-3,000 rpm, and it suddenly jumps up when accelerating or hitting bumps, suspect the plastic laminate with the numbers printed on it has shifted position and the needle is rubbing against it. Something similar happened to all the older K-cars from the mid 1980s. If you look at any one of them, you will see that the turn signal lenses have shifted and are not centered. The glue softens from the heat of the sun, and gravity takes over.
If you suspect shifted laminate is the problem, don't try to remove and reglue it; you'll make a mess of it. Just use a small hobby knife to trim a little bit where the pointer comes through it. 1/32" is plenty. Also, the pointer is either glued on or is just very tight. Work around it. If you try to pry it off, you could bend the shaft and cause more problems.
Saturday, November 28th, 2009 AT 5:17 PM