Retained Accessory Power (RAP) Power Mode

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Retained Accessory Power (RAP) is a power mode that permits the operation of selected customer convenience items for 10 minutes after the ignition switch is turned OFF. RAP power mode is enabled by the BCM.

The BCM:

Controls certain body functions.
Sends out a class 2 message via the serial data line, which enables/disables other modules at the beginning/end of RAP power mode.

Some BCM features, such as the interior courtesy lamps will function after the 10 minute RAP time limit has elapsed. This is normal, and does not mean RAP power mode is malfunctioning. The BCM enables the following functions in RAP Power Mode:

The right and left power rear windows (internal to BCM-if equipped)
Any class 2 module that functions in RAP power mode (that is not hard-wired), is controlled by the BCM via class 2 power mode messages. EXAMPLE: the radio works in RAP power mode due to the BCM controlling it's power mode over the class 2 serial data bus.

RAP is disabled when:

A door is opened.
A low battery voltage is detected by the BCM.
The transition of ignition switch from OFF to ON of ACC.
10 minutes have elapsed after the ignition was turned OFF.

The BCM monitors the ignition switch position, batter voltage and passenger compartment door status to determine whether RAP power mode should be enabled. If the ignition switch transitions from ON to OFF, the battery voltage is within the acceptable range and the passenger compartment doors are closed, the BCM enables RAP power mode. After the 10 minutes has elapsed, the BCM sends a class 2 message to the serial data network. This message commands the other modules to stop functioning, that are controlled by the BCM power mode messages.