WARNING: This page is about a different car, the 1992 Oldsmobile Toronado, 1992 Cadillac Eldorado, and 1992 Buick Riviera. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: PCM Wiring Diagram (1 of 2), 3.8L VIN L - Riviera
Fig 2: PCM Wiring Diagram (2 of 2), 3.8L VIN L - Riviera
Fig 3: BCM Wiring Diagram, 3.8L VIN L - Riviera
Fig 4: PCM Wiring Diagram (1 of 2), 3.8L VIN L - Toronado & Trofeo
Fig 5: PCM Wiring Diagram (2 of 2), 3.8L VIN L - Toronado & Trofeo