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Home >> Chevrolet >> 2006 >> Silverado 1500 HD, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 258 (Retained Accessory Power System) >> Diagnostic Information and Procedures >> DTC B1477 or B1478: Short To Ground In WND RAP Relay Control Circuit >> Circuit Description

Circuit Description

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The BCM interfaces with the vehicle's power distribution system through the WND RAP relay. The WND RAP relay allows the BCM to control the application of power to the feed circuits of the Power Windows. When the ignition switch is in either the ACC or the ON position, the BCM energizes the WND RAP relay by providing B(+) to the WND RAP relay control circuit.

The BCM turns off the WND 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 OFF, with all of the vehicle doors closed, the BCM leaves the WND RAP relay energized for 10 minutes, or until any vehicle door opens.