Test Description

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 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 - Remote Keyless Entry

Step	Action	Yes	No
1	Install a scan tool. Does the scan tool power up?	Go to Step 2	Go to Scan Tool Does Not Power Up in Data Link Communications
2	Turn ON the ignition, with the engine OFF. Attempt to establish communication with the Body Control Module (BCM). Does the scan tool communicate with the LGM?	Go to Step 3	Go to Scan Tool Does Not Communicate with Class 2 Device (W/O Immobilizer)Scan Tool Does Not Communicate with Class 2 Device (W/ 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 toStep 4	Go toPower Mode Mismatch in Body Control System
4	Select the Body Control Module display DTCs function on the scan tool. Does the scan tool display any DTCs?	Go to Step 5	Go to Symptoms - Keyless Entry
5	Does the scan tool display any DTCs which begin with a "U"?	Go to Scan Tool Does Not Communicate with Class 2 Device (W/O Immobilizer)Scan Tool Does Not Communicate with Class 2 Device (W/ Immobilizer) in Data Link Communications	Go to Step 6
6	Does the scan tool display DTC B1000?	Go to Diagnostic Trouble Code (DTC) List in Body Control System	Go to Step 7
7	Does the scan tool display DTC B1327 or B1372?	Go to Diagnostic Trouble Code (DTC) List in Engine Electrical	Go to Symptoms - Keyless Entry