For 1990-2009 cars

### 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.

RAP will end when one of the following conditions is met:

• | The BCM receives an input 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 BCM then sends a serial data power mode message Off-Awake ending the RAP function.

The modules activated by serial data that perform normally during RAP are:

• | The radio

• | The rear seat entertainment (RSE) assembly

• | The vehicle communication interface module (VCIM) (OnStar®)

### Relay Control of Retained Accessory Power (RAP)

The BCM keeps the RAP relay energized during all power modes, except Off-Awake. The RAP relay provides power to the following underhood fuse block fuses:

• | S/ROOF fuse

• | WSW fuse

• | PWR/WNDW fuse