Principles of Operation: Notes
WARNING: This page is about a different car, the 2009 Ford Econoline. 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).
When a vehicle door is ajar and the vehicle speed is less than 15 km/h (9 mph), or the instrument panel dimmer switch is in the DOME LAMP position, the Smart Junction Box (SJB) provides voltage to the courtesy lamp circuit. The SJB controls all interior lighting functions and timing by monitoring inputs from the door ajar switches, the instrument panel dimmer switch, the RKE transmitter and vehicle speed.
Stripped chassis vehicles do not utilize the courtesy lamp system.