I have an 86 firebird (originaly a v-6) and, among other mods, swapped the factory warning light panel for the full gauge, 120mph speedo set from a 90 or 91 (can't remember which year it was). Everything works, but they read wrong. The speedo reads 10 mph slow, the fuel gauge reads 1/4 tank when it's empty, temp reads 10-20 deg high, oil pressure reads 10 psi high. Volts and tach are correct. While reading datastream everything reads correct on the scanner. I've looked at diagrams and haven't seen or heard of a resistor to limit voltage to the dash, just the speed buffer which this dash didn't have. Any help would be greatly appreciated.

Other mods include: drivetrain from an 89 IROC, "F" motor 700R, 92 LT-1 stand-along powertrain management

 

well, factory gauges are not well know for their accuracy, so i would say its just a case of factory gauges doing what they do best.

How do you know they are high if you didnt have them before?

 

I suspected the speedo was off when I was flying by people while doing the speed limit. Then I ran out of gas while showing 1/4 tank. I still had mechanical gauges hooked up and compared them to the dash and also compared to the readings on my scanner data (snap on solus). I have no way of knowing if they worked in the original car, it was a car I picked apart at the salvage yard

 

good luck tryiin to get an 80's style GM gas gauge to work right.

 

That's what I was afraid of but damn they look alot better than the original dash