WARNING: This page is about a different car, the 2002 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Base Radio Circuit, W/ Rear Controls
Fig 2: Base Radio Circuit, W/O Rear Controls
Fig 3: Premium Sound Radio Circuit, W/ Rear Controls (1 of 2)
Fig 4: Premium Sound Radio Circuit, W/ Rear Controls (2 of 2)
Fig 5: Premium Sound Radio Circuit, W/O Rear Controls (1 of 2)
Fig 6: Premium Sound Radio Circuit, W/O Rear Controls (2 of 2)