WARNING: This page is about a different car, the 2003 GMC Safari and 2003 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Scan Tool Does Not Communicate with Class 2 Device Diagnostic Test (1 Of 4)
Courtesy of GENERAL MOTORS CORP.
Fig 2: Scan Tool Does Not Communicate with Class 2 Device Diagnostic Test (2 Of 4)
Courtesy of GENERAL MOTORS CORP.
Fig 3: Scan Tool Does Not Communicate with Class 2 Device Diagnostic Test (3 Of 4)
Courtesy of GENERAL MOTORS CORP.
Fig 4: Scan Tool Does Not Communicate with Class 2 Device Diagnostic Test (4 Of 4)