Any reason why when the car is off the Tach sits at "0" but when running, it pegs right out, even though the car is idling fine? Bad Tach? 1991 Camaro RS Steve C - RI

Yeah, one of the resistors in it went bad.

same here.

If it's always pegged out with the key on, it could be a bad driver circuit. Those are not used anymore so they are hard to find but it's still repairable. I can look if I can find one online.

Lou

Ok.... here it is

The Tach is pegged when the car is off or when you first turn the ignition on.

When you go to turn the car over, the tach returns to zero RPMs, but as soon as it starts, it pegs right out again.

Bad tach?

Steve C - RI

I just bought a cluster off ebay and my tach does the same thing!! I bought it because my temp gauge was off and being an automatic, I don't really need the tach, but I would like to to work correctly.
Any help with fixing it would be appreciated- I still have the old cluster for spares if needed...

Update: Since the tach worked on my old cluster, I simply pulled the tach circuit board from it and swapped it into the replacement cluster. Works perfectly! 21 minutes to access the cluster, swap boards and button it all up!

Suggestion: anyone that has torn down a 3rd gen and had a working tach, pull the board and make it available on the site- obviously you will have a buyer or 2, given that the dealer wanted to sell me a new cluster for $700!

Good job!
Now that you have a bad driver board, would you be willing to donate it for good purposes? I would like to investigate whether it's possible to fix/revive these broken driver boards. I can adjust a working one but not sure how to fix a dead board.

Lou

Yeah, i've got the same problem

Only, mine stays pegged out even with the key off...when i crank, it jumps to 0 then goes around the tach until it pegs out again...in cold weather i can time when my car starts (it starts when the tach hits about 5500)

being an automatic, it's un-needed...but i'd like to have it working =/

mine goes to 0 when cranking then jumps up to about 4500 rpm for a couple seconds before finally pegging out

i got the same problem on my '82 z28
yall know any good ways to just fix it directly and not super expensive?
thankss

My previous response says it all. Go to a junk yard, pull a cluster- actually you don't even have to pull the cluster, just the bezel assembly- remove the circuit board(about 2 1/2 inches by 1 inch) and swap it into your cluster. If the new board is good it should cure the problem...

where is the circuit board at?

http://www.thirdgen.org/techboard/el...meter-fix.html (90-92 Tachometer fix....)