Body Control Systems: Description and Operation

Module Controlled Functions

Body Control Module (BCM)

The Body Control Module (BCM) (located under the passenger side kick panel) has control of the following systems:

- Interior lighting
- Exterior lighting
- Dimmable backlighting
- Battery saver function
- Delayed accessory relay function
- Horn
- Brake shift interlock
- Power door locks
- Remote Keyless Entry (RKE) system
- Anti-theft system (perimeter and passive)
- Remote engine start
- Tire Pressure Monitoring System (TPMS)

Battery Saver

NOTE: Time-out is 1 minute if the vehicle has less than 80 km (50 miles).

The BCM provides automatic shut-off of some system controlled components after a time-out period in order to save battery voltage. A timer in the BCM is started when the ignition is turned OFF and all the doors are closed. When 10 minutes have elapsed, the voltage is automatically shut off by the BCM. While the BCM has voltage disabled, if the ignition state is changed to any position other than OFF, any door becomes ajar, the UNLOCK button of the RKE transmitter is pressed, a valid keypad code is entered, or the instrument panel dimmer switch is pressed, the BCM restores voltage and starts the timer again.

Post Crash Alert Function

The post crash alert is a function controlled by the BCM. If the Restraints Control Module (RCM) determines an impact of enough severity (the air bags may or may not be deployed), the RCM sends a message to the BCM over the High Speed Controller Area Network (HS-CAN) and the post crash alert function is activated. The post-crash alert function activates the hazard lamp function and cycles the horn on 3 times, then off for 4 seconds, and repeats this cycle until the battery is discharged or the function is turned off. The post crash alert function can be turned off by:

- pressing the hazard flasher lamp switch (which may need to be pressed more than once).
- pressing the RKE transmitter UNLOCK button.
- pressing the RKE transmitter PANIC button.

Upfitter System

The upfitter system contains:

- Upfitter relays
- Upfitter switches (located in lower portion of the instrument panel center finish panel)

The upfitter switches each have an indicator that illuminates when the switch is in the on position. The upfitter switches are used to control relays for switching customer installed accessories on and off. The 4 upfitter switches can enable its corresponding relay only when the ignition is in the RUN or ACC state.

Upfitter relays 1 and 2 can support up to a 25 amp output each, upfitter relay 3 can support up to a 10 amp output and upfitter relay 4 can support up to a 15 amp output.