I have a 91 Camaro and have been having trouble with the speedo and tach. The tach has been messed up since I got the car. I reads about twice what the actual engine RPM is. I have not been able to pinpoint what is making it do this. The only thing I can think of is the chip that is below the tach. I am also having trouble with the electronic speedometer. It is a 305 tbi 5 speed car and I converted it to 5.7 TPI. The harness came out of a 1990 automatic. The wires from the 90 to the 91 must have switched positions in the underhood to dash wiring connectors. Does anyone know what colors or positions these wires are in for the two years. I know I speed but would like to know by how much .
Any input is greatly appreciated.



Thanks,


Jason

 

NO IDEAS????!!!

 

seedo i dont know but tach i gothca there.

the tachs have a circuit board on the back and 1 of the little diodes goes bad so the tach starts reading higher and higher until bam its like double. now you can either replace the diode yourself, pay someone else to do it or simply buy a tach or cluster and replace your crapped out board with a new board.

I simply bought a cluster since i had speedo problems to but mine is mechanical not electronic, and swapped the boards. works great now.

 

Thanks for the info. I'll give it a try and let you know how it works out.


Thanks again,


Jason

 

make sure you get one from a v8! the board is "programmed" different for 6 or 8 cylinders i.e.: number of ignition pulses=one revolution.