Principles of Operation: Notes

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

The SJB monitors the door ajar switches, the hood switch and the luggage compartment lid ajar switch. When the SJB receives a signal from one or more of the monitored switch(es) indicating unauthorized entry into the vehicle (if the unauthorized entry is through a passenger door, hood or luggage compartment lid), the SJB intermittently (in regular intervals) grounds the horn relay and also intermittently (in regular intervals) sends voltage to the turn signal lamps. The horn relay closes, supplying voltage to the horn. The SJB cycles the ground to the horn relay and voltage to the turn signal lamps, on and off, while the perimeter alarm system is activated. If the SJB detects an unauthorized entry through the driver door, the Instrument Cluster (IC) issues a chime for 12 seconds and displays TO STOP ALARM START VEHICLE in the message center. If a valid, programmed PATS key does not turn the ignition to the on position within the 12 seconds, the IC issues a message to the SJB over the Medium Speed Controller Area Network (MS-CAN) to activate the perimeter alarm.

An activated alarm can either be deactivated or disarmed.