Principles of Operation

Interior Lighting

Principles of Operation

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

The SJB supplies voltage to the interior lighting system. The interior lighting system illuminates the courtesy lamps to enhance visibility of the interior while a vehicle door is ajar, and the vehicle speed is less than 15 km/h (9 mph). The SJB controls all interior lighting functions and timing by monitoring inputs from the door ajar switches and vehicle speed.

Interior Lamp Arbitrator

The interior lamp arbitrator (a function of the SJB) chooses between the interior lighting, interior mode, interior lighting delay, illuminated entry, illuminated exit and battery saver to determine which feature has precedence of activating and deactivating the interior lamps. The features are prioritized as follows: battery saver, interior mode, interior lighting, interior light delay, illuminated entry, and illuminated exit.

Ambient Lighting

The ambient lighting feature provides illumination to the center console cupholders, the storage bin, and the front and rear footwells. There are a total of 7 LED locations. The ambient lighting feature is powered by the accessory delay relay, which allows the ambient lighting feature to be used independent of the parking lamps status.

The ambient lighting module provides voltage and ground to the LEDs. There are 3 different color LEDs (red, blue, and green) housed within each LED assembly. By illuminating various color combinations, the LEDs are able to produce 7 different colors of ambient light. The ambient lighting switch is an input to the ambient lighting module. With each press of the switch, the ambient lighting module cycles through a different color variation or turns the ambient lighting feature off. The module retains the last color setting between uses.

Battery Saver

The battery saver is internal to the SJB and provides automatic shutoff of the demand lamps (vanity lamps, map lamps and glove compartment lamp) and courtesy lamps after a period of 30 minutes (10 minutes if the lights are on due to a door ajar) has elapsed in order to save battery voltage. A timer in the SJB starts when the ignition is turned to the OFF position. When the time-out period for the lamps has elapsed, the voltage is automatically shut off to the lamps by the battery saver.

To activate the battery saver feature, one of the following events must occur:

- The ignition is transition out of the OFF position
- Any door is opened
- The luggage compartment lid is opened
- The UNLOCK button of the Remote Keyless Entry (RKE) transmitter is pressed
- The keyless entry keypad is used to unlock the vehicle

Field-Effect Transistor (FET) Protection (MKZ Only)

The SJB utilizes a protective circuit strategy for many of its outputs (for example, the headlamp output circuit). Output loads (current level) are monitored for excessive current (typically short circuits) and are shut down (turns off the voltage or ground provided by the module) when a fault is detected. The circuit then resets after an ignition cycle or customer demand of the function (switching the component on, battery saver being energized). When an excessive circuit load occurs several times, a continuous DTC is stored and the module shuts down the output until a repair procedure is carried out. At the same time, the continuous DTC that was stored on the first failure cannot be cleared by a command to clear the continuous DTCs. The module does not allow this code to be cleared or the circuit restored to normal until a successful on-demand self-test proves that the fault has been repaired. After the on-demand self-test has successfully completed (no on-demand DTCs present), the continuous DTC clears and the circuit function returns.