GM Service Manual Online
For 1990-2009 cars only

Serial Data Control of Retained Accessory Power (RAP)

The 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. Components and systems that are active in RAP are also activated anytime the ignition is any position other than OFF.

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

    • The BCM receives an input indicating the opening of any passenger compartment door after the ignition key is out of the ignition.

       Note: The only door that will turn off the radio during RAP is the driver door. This is a function of the radio and will still turn off after the time limit.

    • The BCM internal timer for the RAP expires after approximately 40 minutes.
    • The BCM detects a decrease in battery capacity below a prescribed limit.

Relay Control of Retained Accessory Power (RAP)

The BCM keeps the RAP relay energized during all power modes, except Off-Awake and Crank. The relay is also energized for approximately 40 minutes after shutting the ignition OFF and removing the key, providing no door is opened. The BCM will de-energize the RAP relay a the same time as the serial data message is sent to end RAP.

The devices powered by the accessory relay during the RAP power mode are the sunroof, power window switches and BTSI/Park Lock.