My tach(factory)indicates correctly when the car is running. When the ignition is turned to off, it gives various, eroneous indications, but always returns to normal when the ignition is turned back on. It currently shows 3200...with the ignition off. When the ignition is turned "on" it returns to zero and operates properly after starting. I currently have easy access to the back of the tach...anything I can do to try to correct the problem?

 

Will it go back to zero if you turn the key to on then back to off again without starting the engine?

 

Yes....just turning the ignition to "on" returns the tach needle to zero...but it goes back to 3200 when the ignition is turned back off. I haven't tried any fix yet. I thought I'd get some input before attempting any repair.

 

I see 3 wires in the plug on the back of the tach...pink, black and dark green? It looks like someone has spliced in to them and messed with them. The pink goes to the IGN in the fuse box, dark green to the neg tach terminal, but the 3rd(blk) doesn't come out of the other end of the tape and connect anywhere.

 

I found the 3rd(black) wire...attaches to the ground screw on the driver's side courtesy light screw. Seems like the gage needs power to properly indicate zero with car off.