Relay Controlled Power Mode

The body control module (BCM) uses the discrete ignition switch inputs Off/Run/Crank, Accessory and Run/Crank to distinguish the correct power mode. These circuits are also routed to the Run/Crank and Accessory relays for relay controlled power feeds during the appropriate power mode.

Run/Crank Relay 

The relay uses a hot at all times B+ power source derived from the underhood electrical center. The Run/Crank relay supplies a power signal to the following circuits when the a Run or Crank power mode is selected:

• Backup lamp circuit
• Electronic brake control module (EBCM)
• Engine control module (ECM)
• Ignition control module (ICM)
• Park neutral position switch
• Transmission circuit 1 and 2

Accessory (ACC) Relay 

The accessory (ACC) relay is energized when the Run or Accessory power mode has been selected. The relay uses a Hot At All Times B+ power source derived from the underhood electrical center. The ACC relay is also energized by the BCM to supply power during the retained accessory power (RAP) power mode. The following devices are controlled by this relay:

• Auxiliary power outlets
• EC mirrors
• Ignition lock solenoid
• Power windows
• Power mirrors
• Radio
• Rear compartment lid release
• Sunroof
• Wiper washers