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Home >> Cadillac >> 2002 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 623 (Retained Accessory Power System) >> Diagnostic Information & Procedures >> DTC B1478: Short To Battery In The RAP#1 Relay Control Circuit >> Circuit Description
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Circuit Description

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The BCM interfaces with the vehicle's power distribution system through the RAP#1 relay. The RAP#1 relay allows the BCM to control the application of power to the feed accessory circuits.

When the ignition switch turns from ON/RUN to LOCK or OFF, with all of the vehicle doors closed, the BCM leaves the RAP#1 relay energized for 20 minutes, or until any vehicle door opens and the BCM detects a ground signal in one of the door ajar circuits.