I have an '84 Trans AM which has had EVERYTHING from an '86 TPI car swapped into it. All body harnesses, drivetrain, etc. I recently swapped the car back to carb (got sick of constantly battling driveability and hard starting issues with the TPI), but electrically, it still has all the '86 harnesses in it.

I simply unplugged the EFI harness under the right side of the dash and removed it. The second harness that plugs in at the left side of the firewall (with the headlight harness) is still intact, since I found that it has all the connections for the starter, alternator, distributor, temp gauge, etc.

The car starts up and runs great, problem is now my instrument cluster is dead. I was expecting to have to rewire the VSS to the speedometer, but I thought the rest of the gauges would still work. Not even my gas gauge is working, it's as if the cluster has either lost power or ground? Anyone ran into this?

Does anyone have a clear pinout of the two large connectors under the right side of the dash?

 

I got rid of my ECM in my 86 and I had to wire a ground to the VSS module but all my gauges still work because they are in the engine harness on the driver side of the engine bay.

 

checking the fuses would be the 1st thing

 

Thanks, that's what it turned out to be. Sometimes you get so deep into things you forget to check the simple stuff.