WARNING: This page is about a different car, the 2004 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: PCM Status Failure, Serial Link External Fault - Diagnostic Procedure (Test Step 1)
Courtesy of DAIMLERCHRYSLER CORP.
Fig 2: PCM Status Failure, Serial Link External Fault - Diagnostic Procedure (Test Steps 2 - 4)