Retained Accessory Power: Overview Chevrolet Silverado 1500 HD

Scheme 1

Begin the system diagnosis with Diagnostic System Check - Retained Accessory Power . The Diagnostic System Check will provide the following information

1. Class 2 communications status
2. "U" codes which indicate module communication or circuit failure
3. "B" codes which indicate a possible body function or circuit failure
4. The status of any "U" or "B" codes

Test Description

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

1. This step verifies that the RAP power mode function is malfunctioning by checking functions internally enabled by the BCM.

3. 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 malfunctions 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.

4. This step is checking for DTCs in the BCM.

5. The presence of DTCs which begin with "U" indicate that other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Scheme 2