GM Service Manual Online
For 1990-2009 cars only

Serial Data Control of Retained Accessory Power (RAP)

The class 2 modules receive the power mode message from the body control module (BCM) over the serial data circuits, indicating when the retained accessory power (RAP) power mode is current. The BCM monitors the ignition switch position, battery condition and passenger compartment doors status to determine whether RAP should be initiated. The modules then support the operation of the systems under their control as required by their RAP power mode operation.

The BCM then sends a serial data power mode message Off-Awake ending the RAP function, when one of the following conditions is met:

    • The BCM receives an input or class 2 message indicating the opening of any compartment door.
    • The BCM internal timer for the RAP expires after approximately 10 minutes.
    • The BCM detects a decrease in battery capacity below a prescribed limit.

The following modules maintain their functionality during the RAP power mode:

    • Radio
    • Vehicle Communication Interface Module (VCIM)

Relay Control of Retained Accessory Power (RAP)

The power windows are controlled through the WND retained accessory power (RAP) relay. The body control module (BCM) keeps the WND RAP relay energized during all power modes, except Off-Awake. The WND RAP relay provides power for power windows operation.