tachometer help

I have a 97 grand prix with a 3.8 i noticed that the tach was jumping when i went to starting the car. The tach was jumping with the key on and engine was off. thank you

The tach gets its signal from the ignition control module through the PCM module and then to the tachometer. Remove and reseat the electrical connector. Check for bad contacts or corrosion. Also, make sure the ignition control module ground is good.