Hi.

Did any of you ever experience the phenomena when the car's battery is drained. The Tach really comes alive when you turn the ign. on and the needle goes all over the place. Unfortunately this happens on my car 8 times out of 10 when I drive it. Could there be a loose connection or does the tachs have a history of breaking? I'm driving a 86 IROC.

Thanks.

 

Check the tach connection at the coil - it should be a white wire going into the harness. You may also have a tach filter - a 1/2" diameter device mounted to the fire wall, behind the distributor - that the white wire goes through, before going into the harness. The wires may have an intermittant open at the coil, the tach filter, or in the harness. Try routing another (temporary) wire from the cluster to the coil to see if it is in fact an intermittant wire. The white tach wire to the cluster is on pin 11 of connector C1. If the "temporary" test wire does not solve the problem, either the tach filter (if you have one) is defective, or the tach itself has a problem.

Tim