Retained Accessory Power System: Other Chevrolet Silverado 2500

Data

Battery Voltage: The scan tool displays the battery system voltage.

RAP Timer: The scan tool displays the seconds left before the BCM turns the RAP relay OFF. The BCM uses this feature to allow the operation of the radio and the power windows for up to 1198 seconds/20 minutes after the ignition is turned OFF. After the time has elapsed or the door is opened the BCM will open the ground circuit for the RAP relay.

Input 1

Drivers Door Jamb Switch: The scan tool displays the position of the drivers door. The scan tool displays ACTIVE when the drivers door is open.

Ignition 1: The scan tool displays the position of the ignition switch. The scan tool displays ACTIVE when the ignition switch is in the RUN or CRANK position.

Ignition 3: The scan tool displays the position of the ignition switch. The scan tool displays ACTIVE when the ignition switch is in the RUN position only.

Ignition Power Mode: The scan tool displays the position of the ignition switch. The scan tool displays OFF, RUN, CRANK and UNKNOWN. The UNKNOWN display is when the BCM can not determine the position of the ignition switch.

Key In Ignition: The scan tool displays the position of the ignition key in the ignition switch cylinder. The scan tool displays YES when the ignition key is completely inserted into the ignition switch cylinder. The BCM uses this data in controlling the operation of the reminder chime feature.

RAP Relay Feedback: The scan tool displays the state of the RAP relay. The scan tool displays ON when the BCM activates the RAP relay.

Outputs

RAP Relay: The scan tool displays the commanded state of the RAP relay. The scan tool displays ON when the BCM allows the RAP relay to go to ground. The BCM will allow operation of the radio and the power windows with the ignition OFF and the doors closed for up to 1198 seconds, approximately 20 minutes.

Scheme 48

Important Preliminary Checks Before Starting

1. Perform the «Diagnostic System Check - Retained Accessory Power»(ref-176709-S08440955402005051200000) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control module(s) can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to «Retained Accessory Power (RAP) Description & Operation»(ref-176709-S31264998322005051200000) .

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to TESTING FOR INTERMITTENT & POOR CONNECTIONS .

Retained Accessory Power (RAP) Power Mode

RAP is a vehicle power mode that permits the operation of selected customer convenience items after the ignition switch is turned OFF. These selected items will remain in operation until a passenger compartment door is opened or until the RAP function timer reaches its shut-off limit.

The BCM turns OFF the RAP function and de-energizes the RAP#1 relay when one of the following conditions are met

1. The BCM senses the opening of any door or the liftgate.
2. The BCM detects a decrease in battery capacity below a prescribed limit.
3. The BCM receives a message from its internal timer indicating the end of the RAP period after 20 minutes.
4. The transition from OFF to RUN/ON of the ignition switch.

RAP Relay #1

The body control module monitors the ignition switch position, battery condition and passenger compartment door status to determine whether RAP should be initiated. If the ignition switch transitions from RUN/ON to OFF, the battery level is within the acceptable range and the passenger compartment doors are closed, the body control module energizes the RAP#1 relay. This provides power for the following

1. RAP Relay #2 Control Signal
2. DIC
3. Rear Seat Audio Controller
4. Left and Right Steering Wheel Control Switches.
5. Left Front and Rear Power Window Control Switches
6. Left Front and Rear Power door lock Switches
7. Radio
8. OnStar, VIU

RAP Relay #2

When the BCM commands the RAP function active, RAP#1 relay supplies a signal to RAP#2 relay's control circuit. RAP#2 relay then supplies an isolated fused power source to the following accessories

1. Right Front and Rear Power Window Control Switches
2. Right Front and Rear Power door lock Switches
3. Power Sunroof