I'm just finishing up my swap and I have everything wired in. But I can't figure out how to program the computer and I can't get the engine to turn over with the key. When I turn the key to on, the fuel pump will turn on. I know I need to disable VATS in the PCM but when I try to read data from the PCM (with the key at the on position), it just says invalid signal (Tunercats). The LT1 is a 94 from a B-Body, and I think that the wiring harness is from an F-body. The only thing that I can think of is that the PCM could be wired wrong. Any ideas? Also, why wouldn't turning the key all the way fire the starter? Firing the starter manually doesn't accomplish much other than turning the engine. I have power to all of the interior and the gauges.

 

Ask moderator to move thread to Engine swap, sub forum LSx LTx, you will get more responses there. Have you looked the pinouts for ECM as well as the harness?