B1477

Circuit Description
The retained accessory power function allows certain systems to operate for 20 minutes after the ignition switch is turned OFF. Examples of systems that retain power include the following systems:
- The radio
- The power windows

The BCM monitors the following items:
- The ignition switch position
- The voltage on CKT 755

The BCM will command the RAP relay to turn ON by grounding CKT 755 when the following conditions exits.
- All of the doors are closed.
- The ignition switch is in the OFF position.

DTC B1477 will set if the following conditions exist:
- The BCM detects an open or a short to ground in CKT 755.
- The RAP relay is commanded ON.

Conditions for Setting the DTC
- The BCM does not detect battery voltage on CKT 755 (open or shorted to ground) with the ignition switch in the OFF position.
- The system voltage is between 9.0 - 16.0 volts.
- The above conditions exist for 0.5 seconds.

Action Taken When the DTC Sets
- If CKT 755 is open, the following items will not operate if the ignition switch is turned OFF and all of the doors are CLOSED:
- The radio
- The power windows
- If CKT 755 is shorted to ground, the following items will not operate if the ignition switch is turned OFF:
- The radio
- The power windows

Conditions for Clearing the MIL/DTC
- DTC B1477 will clear immediately when one of the following actions occurs:
- The condition that sets the fault is corrected when the ignition is in the OFF position.
- The next ignition cycle begins.
- A history DTC will clear after 100 consecutive ignition cycles without a fault present.
- History and current DTCs may be cleared using a scan tool.

Diagnostic Aids
Important: Use the appropriate probe from the J 35616-A connector test adapter kit for any probing of the fuse blocks or relay blocks in this table. Use of the appropriate probe prevents damage to the fuse blocks or relay blocks.
- Always diagnose the first current DTC that is listed on the scan tool.
- Verify that the scan tool displays DTC B1477 as a current code before you perform diagnostics.
- Inspect the following components:
- The wiring
- The terminals
- The connectors
- Refer to Intermittents and Poor Connections Diagnosis in Overall Vehicle Information / Testing and Inspection.

Step 1:

Steps 2 - 6:

Steps 7 - 12:

Steps 13 - 16:

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies the condition of the RAP relay fuse and CKT 542 to the Body relay block.
3. This step determines if CKT 755 (BLK) is shorted to ground.
4. This step determines if the BCM is operating correctly.
5. This step determines if CKT 542 is open to the RAP relay in the Body relay block.
6. This step determines if one of the following conditions exists:
- CKT 542 (RED) is shorted to ground.
- CKT 542 (RED) is open in the underhood fuse block.