Test Description

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

A partial loss of communication in the class 2 serial data circuit uses a different procedure than a total loss of communication of the class 2 serial data circuit.

The following DTCs may be retrieved with a history status. These DTCs are not the cause of the present condition.

U1300
U1301
U1305

A State of Health DTC with a history status may be present along with a U1000 or U1255 with a current status. This indicates that the malfunction occurred when the ignition was on.

Normal class 2 serial data communication cannot take place until the Power Mode Master (PMM) module sends the appropriate power mode message. If the PMM does not send a wake-up message, other modules on the class 2 serial data circuit may not communicate.

If there are no current DTCs that begin with the letter "U", the communication concern has been repaired.

The communication concern may have prevented diagnosis of the customer complaint.

Fig 1: Scan Tool Does Not Communicate With Class 2 Device (1 Of 3)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Scan Tool Does Not Communicate With Class 2 Device (2 Of 3)

Courtesy of GENERAL MOTORS CORP.

Fig 3: Scan Tool Does Not Communicate With Class 2 Device (3 Of 3)

Courtesy of GENERAL MOTORS CORP.