I had to replace my rear main seal last weekend, so I moved a lot of stuff around.When I started the car back up the OER tach went from 650 at idle to 900 but wont go any higher.I tested another tach I have and it worked fine with the signal off the coil and the power from the battery and grounded.I can't remember if the OER tach gets grounded.I used Jim's modified circuit panel pic to install mine. Does this sound like a ground problem.I don't have a filter on it but it never did bounce around.

Thanks for the help