Test Description
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 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.
- This step verifies that the retained accessory power (RAP) power mode function is malfunctioning by checking functions internally enabled by the body control module (BCM).
- The BCM sends class 2 messages to other control modules via the serial data link, allowing them to operate in RAP power mode. 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.
- This step is analyzing the BCM for DTCs.
- The presence of DTCs that begin with "U" indicate another module is not communicating. The specified procedure will compile all the available information before tests are performed.