Principles of Operation: Notes

WARNING: This page is about a different car, the 2013 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

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

The SJB monitors the multifunction switch position by sending multiple voltage signals to the multifunction switch. When the multifunction switch is in the LH or RH TURN positions, or the hazard lamp switch is pressed, that input signal is routed to ground.

When the SJB receives a request for a turn signal or hazard lamps, the SJB supplies voltage to the front turn lamps and sends a message to the Body Control Module B (BCM-B) to flash (sequential or non-sequential) the rear lamps.

The timed on/off cycle is determined by the SJB and is set to flash approximately 80 times per minute if both the front and rear turn lamps operate correctly. If an individual turn signal lamp is determined inoperative by the SJB or the BCM-B, the SJB and the BCM-B (non-sequentially) flash the remaining turn lamp(s) approximately 160 times per minute.

The timed on/off cycle for the hazard lamps is set to flash approximately 80 times per minute.

The rear turn lamps are set to flash sequentially from the inboard lamp to the outboard lamp. The rear lamps do not flash sequentially for the hazard function.