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Home >> Cadillac >> 2002 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 536 (Retained Accessory Power System) >> Diagnostic Information and Procedures >> DTC B1478: Short To Battery In RAP Relay Control Circuit >> Circuit Description
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Circuit Description

WARNING: This page is about a different car, the 2002 Buick Regal and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.

The Body Control Module (BCM) interfaces with the vehicle's power distribution system through the RAP relay. The RAP relay allows the BCM to control the application of power to the feed circuits of 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 grounding 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 ACCESSORY to UNLOCK 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 one of the door ajar circuits.