i've got a short in the tachometer wiring how do i fix it

Being an electrical issue, there are sooo many places the problem could be coming from, this question forum could get VERY lengthy. Could be out at the tach, the wiring "sheet" behind the dash, in the wiring harness under the dash, out under the hood, etc. For now I would say check for codes in the OBD II system and check your grounds.

I fixed this one (a very long time ago) by replacing the coil. It seems that while the engine ran fine, the coil must have been feeding back into the module. Of course, I had spare parts to try at the time so guesses didn't cost anything. It isn't usually the Tach itself but something else in the system that failed.