GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The body control module (BCM) controls some retained accessory power (RAP) functions through the RAP supply voltage circuit. When the ignition switch is in either the ACC or the ON position, the BCM provides battery voltage to the RAP supply voltage circuit. When the ignition switch turns from ON or ACC to OFF, with all of the vehicle doors closed, the BCM still provides battery voltage to the circuit for 10 minutes, or until any vehicle door opens.

DTC Descriptors

This diagnostic procedure supports the following DTC:

DTC B1477 Retained Accessory Power Circuit Low

Conditions for Running the DTC

The system voltage must be between 9-16 volts.

Conditions for Setting the DTC

    • The BCM detects a short to ground in the RAP supply voltage circuit when the BCM is trying to energize the circuit.
    • The condition above must be present for more than 1 second.

Action Taken When the DTC Sets

    • The BCM stores DTC B1477 in memory.
    • The devices powered by the RAP supply voltage circuit will not operate.

Conditions for Clearing the DTC

    • A current DTC clears when the malfunction is no longer present.
    • A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Step

Action

Yes

No

Schematic Reference: Retained Accessory Power (RAP) Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn OFF the ignition.
  2. Disconnect the first device powered by the retained accessory power (RAP) supply voltage circuit, the RAP relay, or the sunroof/power roof module connector.
  3. Turn the ignition ON, with the engine OFF.
  4. Retrieve DTCs from the body control module (BCM).

Does the DTC  B1477 still set as current?

Go to Step 3

Go to Step 4

3

Test the RAP supply voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 5

4

Inspect for poor connections at the first device powered by the RAP supply voltage circuit, the RAP relay, or the sunroof/power roof module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 6

5

Inspect for poor connections at the harness connector of the BCM . Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 7

6

Replace the first device powered by the RAP supply voltage circuit, the RAP relay, or the sunroof/power roof module. Refer to Control Module References for replacement, setup, and programming, if applicable.

Did you complete the replacement?

Go to Step 8

--

7

Replace the BCM . Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 8

--

8

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

Go to Step 1

System OK