Express 1500 RWD V8-5.3L VIN T (2004)
Accessory Delay Module: Description and Operation
RETAINED ACCESSORY POWER (RAP) DESCRIPTION AND OPERATION
RETAINED ACCESSORY POWER (RAP) POWER MODE
RAP is a power mode that permits the operation of some accessories for up to 10 minutes after the ignition switch is turned OFF. The RAP power
mode is enabled by the body control module (BCM).
The BCM:
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Controls certain body functions.
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Sends out a class 2 message via the serial data link, which enables/disables other modules at the beginning/end of the 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 the RAP power mode is malfunctioning. The BCM enables the following functions in RAP Power Mode:
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The right and left power windows through the WND RAP relay.
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Any class 2 module that functions in RAP power mode and is not connected to the WND RAP relay, is controlled by the BCM via class 2 power
mode messages. EXAMPLE: The radio works in RAP power mode because the BCM sends it a class 2 message telling it that the power mode is
RAP.
RAP is disabled when:
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A door is opened.
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Low battery voltage is detected by the BCM.
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The ignition switch transitions from OFF to ON or ACC.
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10 minutes have elapsed after the ignition was turned OFF.
The BCM monitors the ignition switch position, battery 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 10 minutes have elapsed, the BCM sends a class 2 message to the serial
data network. This message commands the other modules that are power moded by the BCM to stop functioning.
WND RAP RELAY
The BCM controls the WND RAP relay's coil circuit using high side drive. The output of the relay is used to supply battery voltage to the power
windows. The WND RAP relay also provides voltage to the power windows when the Accessory power mode is selected.
