I recently did an engine swap on my 1994 Fleetwood Brougham. It has the LS1 motor, and the engine I installed was from a 1996 Fleetwood Brougham. Everything is installed and hooked up, but I have no power to the stater, and also no spark. I have power to the dash and everything else on the car. I would appreciate any suggestions as to what the problem may be. I was thinking perhaps something with the security system. Since I swapped the motor and computer, would my original key still fire the car? Is a 96' computer compatible in a 94' car? Please help!

 

if you swapped the engine and computer from another cady you will need the key that was programed to that cady. But then i could be wrong on this but you also swapped in an engine and computer that runs on a OBDII system into a car that has OBDI which may have something to do with why you may not be getting power to starter and spark. Did you use the wiring harness from the 96 cady aswell or are you using the 94 wiring. also check your grounds for the starter just incase you missed something along the way.

 

there should be a module for the keyit a stand alone box control key input signal

so have someone turn the key and u need to check for power either at the starter purple wire or ignition module i think its the yellow wire for battery voltage

 

The '96 computer is looking for a signal from the BCM signaling that it has received the correct key code. Since you have the '94 BCM, the '96 PCM isn't getting that confirmation.
Why not install the original('94) PCM?