Principles of Operation

Anti-Theft

Principles of Operation

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

The SJB controls the operation of the perimeter alarm based on inputs received over the Medium Speed Controller Area Network (MS-CAN) from the Driver Door Module (DDM) and the Remote Function Actuator (RFA) module. If the SJB receives an input indicating an unauthorized entry into the vehicle, the SJB activates the perimeter alarm by sounding the horn and flashing the turn signals in regular intervals.

The DDM receives hardwired inputs from the driver door lock control switch and the door disarm switch (part of the driver door latch). The DDM then broadcasts the status of these 2 switches over the MS-CAN to the RFA module and the SJB.

The RFA module receives hardwired inputs from the passenger door lock control switch, hood switch, all door ajar switches, and the liftgate ajar input from the Liftgate/Trunk Module (LTM) and the keyless entry keypad. The RFA module also receives wireless signals from the Intelligent Access (IA) key for the operation of the IA feature and Remote Keyless Entry (RKE). The RFA module then broadcast the status of these inputs over the MS-CAN to the SJB.

Once the SJB receives the inputs from the DDM and RFA module, it either activates, deactivates, or triggers the perimeter alarm.

Alarm Event PIDs

The RFA module and SJB both have PIDs available that show what caused the last alarm events. The SJB has 4 alarm event PIDs and are AL_EVT1 thru 4, and the RFA module has 8 alarm event PIDs 1 thru 8_Alrm_Trg. The most recent alarm event is always listed in the first alarm event or trigger PID. These PIDs display what caused the alarm to trigger and can be a very useful tool when trying to identify the cause of an alarm trigger.