Principles of Operation
WARNING: This page is about a different car, the 2010 Mercury Milan, 2010 Lincoln MKZ, and 2010 Ford Fusion. 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 Smart Junction Box (SJB) monitors the multifunction switch position by sending voltage signals (for the LH and RH turn input) to the multifunction switch. When the multifunction switch is in the LH or RH TURN positions that input signal is switched to ground.
The SJB monitors the request for the hazard lamps by sending a voltage signal to the hazard flasher lamp switch. For MKZ, the hazard flasher lamp switch is integrated into the Front Controls Interface Module (FCIM).
When the SJB receives a request for a turn signal or hazard lamps, the SJB supplies voltage to the appropriate turn lamps.