WARNING: This page is about a different car, the 2003 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Rear Channels Short Together Or To Ground Diagnostic Procedure (1 Of 2)
Courtesy of DAIMLERCHRYSLER CORP.
Fig 2: Rear Channels Short Together Or To Ground Diagnostic Procedure (2 Of 2)