I figure you guys are the best to ask with electronics questions, so here it goes. My tach is going crazy! Sometimes it's fine, but most of the time the needle jumps around and just spazzes out in general. Sometimes it reads zero while I'm driving. Do f-bodies have a tach sending unit, or is it all controlled by the computer? Could it be some kind of interference causing the wire to pick up a signal from something else? Thanks in advance for helping my sanity!
-John

 

Sounds like you have a bad connection either where the gauges plug into the dash or the tach itself.

 

Well, I've checked the connections where the gauge cluster plugs in, so I guess maybe the tach is taking a crap on me then. It's really annoying driving around with the tach needle having a seizure. Grrrrrr

 

is this an aftermarket tach or the stock one...

im guessing stock....my buddy had that happen to him on his import.... he had to spend a grand to fix it...so i dont know if its the same thing.....its prob a sending unit

 

Actually, I have had both the factory tach, and an aftermakerket 5" tach do the same exact thing. The aftermarket tach was tapped into the the tach wire from the Body Control module behind the pass. side kick panel. I guess this means it's upstream in the wiring somewhere. Any other guesses? Can anyone verify if we have a sending unit or not?
-John

 

it sounds like a sending unit prob....have a speed shop take a look at it so u know for sure