Test Description

WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The number(s) below refer to the step number(s) on the diagnostic table.

2: Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
5: The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Diagnostic System Check - Door Systems

Step	Action	Yes	No
1	Install a scan tool. Does the scan tool power up?	Go to Step 2	Go to xScan Tool Does Not Power Up in Data Link Communications
2	IMPORTANT: If the outside mirrors are equipped with turn signals in the mirrors, the left and right turn signals must be activated prior to attempting to establish communication with the driver and passenger door modules. Turn ON the ignition, with the engine OFF. Attempt to establish communication with the following modules: The driver door module The passenger door module The lift gate module The body control module The powertrain control module The instrument panel cluster Does the scan tool communicate with all of the modules?	Go to Step 4	Go to xScan Tool Does Not Communicate with Class 2 Device (W/O Immobilizer) in Data Link Communications
3	IMPORTANT: The engine may start during the following step. Turn OFF the engine as soon as you have observed the Crank power mode. Access the Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool. Rotate the ignition switch through all positions while observing the ignition switch power mode parameter. Does the ignition switch parameter reading match the ignition switch position for all switch positions?	Go to Step 4	Go to xxPower Mode Mismatch in Body Control System
4	With the scan tool, select the Display DTCs function for each of the following modules: The driver door module The passenger door module The lift gate module The body control module The powertrain control module The instrument panel cluster Does the scan tool display any DTCs?	Go to Step 5	Go to Symptoms - Doors
5	Does the scan tool display any DTCs which begin with a "U"?	Go to xScan Tool Does Not Communicate with Class 2 Device (W/O Immobilizer) in Data Link Communications	Go to Step 6
6	Does the scan tool display B1000 for any of the modules?	Go to xDiagnostic Trouble Code (DTC) List in Body Control System	Go to Diagnostic Trouble Code (DTC) List