Body Control Systems: Description and Operation

Module Controlled Functions

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

Multifunction Electronic Modules

There are 2 multifunction electronic modules on this vehicle. They include the:

- Body Control Module B (BCM-B) (located in the RH side of the luggage compartment behind the RH quarter panel structure support)
- SJB (located behind the RH A-pillar lower trim panel)

Body Control Module B (BCM-B)

The BCM-B controls multiple vehicle systems which include:

- Ambient lighting
- Convertible top
- Window function inhibit (convertible)
- Luggage compartment lid release inhibit (convertible)
- Reverse lamps
- Rear stop/turn lamps

Smart Junction Box (SJB)

The SJB is a combination of a multifunction electronic module and an interior fuse panel. The SJB functions control multiple vehicle systems which include:

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

Battery Saver

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

The SJB provides automatic shut-off of some system controlled components after a time-out period in order to save battery voltage. A timer in the SJB 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 SJB. While the SJB 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 SJB restores voltage and starts the timer again.

Post Crash Alert Function

The post crash alert is a function controlled by the SJB. 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 SJB 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.