Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2006EXPRESS 3500 V8-6.0L VIN UREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSBODY CONTROL MODULEDESCRIPTION AND OPERATIONRETAINED ACCESSORY POWER (RAP)
2006 Chevrolet Express 3500 V8-6.0L VIN U
Retained Accessory Power (RAP)
2006 Chevrolet Express 3500 V8-6.0L VIN USECTION Retained Accessory Power (RAP)
RETAINED ACCESSORY POWER (RAP) DESCRIPTION AND OPERATION
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.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.