Accessory Delay Module: Description and Operation

GENERAL DESCRIPTION
Retained Accessory Power (RAP) is a standard feature. The system allows the radio, wipers, power windows, trunk lid release and console compartment lamp to be operated for ten minutes after the ignition has been turned off. The system will shut down before ten minutes has elapsed if a door is opened. Turning the ignition to RUN and then back to OFF will reset the RAP system for another ten-minute interval.

The main components of the RAP system are the Body Computer Module (BCM), Door Ajar Switches, two RAP relays, RAP Circuit Breaker and several fuses (see schematic).

When the ignition is turned to RUN the BCM turns on the two RAP relays. When the ignition is turned off the BCM starts an internal timer and keeps the relays energized for ten minutes or until the BCM detects that a door has been opened through the door ajar switch inputs.

The RAP relays are wired in parallel with the Ignition Switch. This allows the circuits powered by the RAP relays to be powered through the Ignition Switch should the RAP circuits malfunction.

CIRCUIT OPERATION

Enabling
When the ignition is turned to RUN the BCM grounds the coils of the RAP relays through CKT 707 at terminal 2A10 and both relays energize. After the ignition is turned off the BCM starts an internal ten-minute timer while keeping the RAP relays energized.

Battery voltage is applied at all times through Fuse D9, Maxi Fuse 2 and respective CKTs 440 and 1446 to the coils/contacts of RAP ACC Relay "A" and RAP Ignition 3 Relay.

When the RAP relays are energized battery voltage is applied through the contacts of RAP ACC Relay "A," CKT 4, Fuses Al and A3 and CKTs 93 and 41 to the Wiper/Washer Switch, the Radio Control Head and the Remote Radio Receiver. The radio and wiper system can now operate. Battery voltage is also applied through the contacts of RAP Ignition 3 Relay, CKT 70, RAP Circuit Breaker and CKT 76 to the power window/trunk lid release systems and the Console Compartment Lamp.

The RAP circuits can be tested by entering diagnostics and selecting BCM Output BO03. When the output is LO the RAP relays should energize, and when the output is HI the RAP relays should de-energize.

Disabling
The BCM disables RAP by removing ground from CKT 707. The RAP relays then de-energize, cutting off power to the accessory circuits. The BCM disables RAP after the ten-minute timer has expired or beforehand if a door is opened.

The BCM monitors the position of the doors through the Door Ajar Switches at terminals 2A2 and 2A3. When a door is opened the Door Ajar Switch closes and grounds the respective door ajar input terminal at the BCM. The Door Ajar Switches open when the doors are closed and the BCM senses an open circuit at the door ajar input terminals.

The door ajar circuits can be tested by entering diagnostics and selecting BCM Inputs B103 or B104. The input should read LO when the door is opened and HI when the door is closed. A problem in the door ajar circuits also would cause a problem with courtesy light control.