B1477

DTC B1477

CIRCUIT DESCRIPTION
The body control module (BCM) interfaces with the vehicles power distribution system through the retained accessory power (RAP) relay. The RAP relay allows the BCM to control the application of power to the feed circuits to the sunroof and the power windows. When the ignition switch is in either the ACC or the RUN position, the BCM energizes the RAP relay by applying battery voltage to the RAP relay control circuit.

The BCM turns OFF the RAP relay when the ignition switch is in the START position. The RAP feature, therefore, disables during engine cranking.

When the ignition switch turns from ON or ACC to LOCK or OFF, with all of the vehicle doors closed, the BCM leaves the RAP relay energized for 10 minutes, or until any vehicle door opens and the BCM detects a ground signal in 1 of the door ajar circuits.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC B1477 Retained Accessory Power Circuit Low

CONDITIONS FOR SETTING THE DTC
- The BCM detects no voltage at the RAP relay control circuit when the BCM is trying to energize the RAP relay.
- The above condition must be present for more than 300 milliseconds.

ACTION TAKEN WHEN THE DTC SETS
- The BCM stores DTC B1477 in memory.
- The RAP relay powered functions will not operate.
- The circuits powered by the RAP relay will never be powered if the relay control circuit is open.

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.

TEST DESCRIPTION

Steps 1 - 13:

The numbers below refer to the step numbers on the diagnostic table.
2. Listen for an audible click when the RAP relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. Verifies that the BCM is providing voltage to RAP relay.
4. Tests for an open in the ground circuit to the RAP relay.
5. Tests if voltage is constantly being applied to the RAP relay.