my buddy hooked up the tach in an 80 Camaro he bought & when you turn the key on, it zeros out but when it's running the needle buries itself @ 7k even if the car is idleing.

what should we check?

My guess is everything is connected correct "when you turn the key on, it zeros out" You can make sure it has a good ground. The ground trace on the circuit card runs from the cluster connector to the left side of the cluster then back to the tach then on to the temp gauge, lots of trace for possible cuts.

Another check is the tach filter. The tach should work without it as it's there to filter out radio noise. You can try bypassing it.

Most likely the tach printed circuit board is the problem. Used parts should inexpensive as there's not as big a demand for the second design tach as the first design. The first design has the same movement and circuit board as the 70 - 72 Chevelle.


PM for info on used filter or circuit board.

Thank you Mr. Colby.
now we have a place to start looking & I will pm ya if we need a circuit board.