85 Trans Am Tach Issue - Third Generation F-Body Message Boards

1985blktransam · 09-15-2008, 12:39 PM

Hi:

I have an issue my my Tachometer that stopped working. All the other gauges work.

Without removing the entire cluster, I purchased another cluster from another 85 Trans Am with same 305H engine. Removed that Tachomter Gauge and replaced into my cluster on my 85 Trans Am. The match is perfect and it does work, but is reading is 5K higher than what is should be, around 7500.

I figured to give it a shot before removing the cluster and send it out for repair.

Any help would be greatly Appreciated

Thanks
Rob

gmpptech · 09-17-2008, 09:19 PM

Does your car have MSD ignition or similar equipment? If it does it has multiple sparks per fire, especially at lower rpm's. You will need to get your signal from the box itself to get the tach to read right.

1985blktransam · 09-17-2008, 09:36 PM

Engine and Ignition System is all GM.

Thanks