where is the pcm located on a 1996 cadillac seville sls

PCM is located in the driver's front of engine bay sorta behind the headlamp module. It is contained in it's own plastic compartment. Make sure you have good positive and ground connections at the battery. The Positive cable especially can cause a problem where it is a dual connection. There was a bulletin to add a washer between the two cables and the lead ring terminal. If that checks out good, you may a PassKey issue.