Principles Of Operation

Interior Lighting

Principles of Operation

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

When a vehicle door is ajar with the vehicle speed less than 15 km/h (9 mph) or 5 km/h (3 mph) for puddle lamps, or a request from the instrument panel dimmer switch is received, the SJB provides voltage to the interior courtesy and puddle lamp circuits. The SJB controls all interior lighting functions and timing by monitoring inputs from the door ajar switches, the instrument panel dimmer switch, the Remote Keyless Entry (RKE) transmitter and vehicle speed.

Interior Lamp Arbitrator

The SJB chooses between the interior lighting, dome defeat, interior lighting delay, illuminated entry, illuminated exit and battery saver to determine which feature has precedence of activating and deactivating the interior lamps.

Ambient Lighting - Fusion/Milan

The ambient lighting feature provides illumination to the center console cup holders, the storage bin, and the front and rear footwells 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 (red, blue and green) LEDs 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 ambient lighting 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.

Ambient Lighting - MKZ

The Interior Lighting Control Module (ILCM) provides voltage to the LEDs. There are 4 different color LEDs (red, blue, green and white) 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 select switch and ambient lighting dimmer switch are inputs to the ILCM. With each press of the ambient lighting select switch, the ILCM cycles through a different color variation. With each press of the ambient lighting dimmer switch, the ILCM changes the brightness setting of the ambient lighting or turns the ambient lighting feature off. The module retains the last color and brightness setting between uses.

Battery Saver

NOTE: Time-out is 1 minute if the vehicle has less than 80 km (50 miles).

The SJB provides automatic shut-off of the demand lamps and courtesy lamps after a 10-minute time-out period in order to save battery voltage. A timer in the SJB is started when the ignition is turned to the OFF position and all the doors are closed. When the 10-minute time-out period has elapsed, the voltage is automatically shut off to the lamps by the SJB.

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

- The ignition is turned to any position other than OFF.
- Any door becomes ajar.
- The UNLOCK button of the RKE transmitter is pressed.
- A key is inserted into the ignition lock cylinder.
- A valid keypad code is entered.
- The luggage compartment lid is opened.
- The instrument panel dimmer switch is placed in the DOME LAMP position.
- The headlamp switch is placed in the PARKING LAMPS or HEADLAMPS ON position.
- The multifunction switch is placed in the FLASH-TO-PASS position.
- The key is inserted into the ignition lock cylinder.

Field-Effect Transistor (FET) Protection

Field-Effect Transistor (FET) is a type of transistor that when used with module software can be used to monitor and control current flow on module outputs. The FET protection strategy is used to prevent module damage in the event of excessive current flow.

The SJB utilizes a FET protective circuit strategy for many of its outputs (for example, a 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 event is detected. A continuous DTC is stored at the fault event and a cumulative counter is started.

When the demand for the output is no longer present, the module resets the FET circuit protection to allow the circuit to function. The next time the driver requests a circuit to activate that has been shut down by a previous short (FET protection) and the circuit remains shorted, the FET protection shuts off the circuit again and the cumulative counter advances.

When the excessive circuit load occurs often enough, the module shuts down the output until a repair procedure is carried out. Each FET protected circuit has 3 predefined levels of short circuit tolerance based on the harmful effect of each circuit fault on the FET and the ability of the FET to withstand it. A module lifetime level of fault events is established based upon the durability of the FET. If the total tolerance level is determined to be 600 fault events, the 3 predefined levels would be 200, 400 and 600 fault events.

When each tolerance level is reached, 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 operation until a successful self-test proves that the fault has been repaired. After the self-test has successfully completed (no on-demand DTCs present), DTC B106E and the associated continuous DTC (the DTC related to the shorted circuit) automatically clears and the circuit function returns.

When the first or second level is reached, the continuous DTC (associated with the short circuit) sets along with DTC B106E. These DTCs can be cleared using the module on-demand self-test, then the Clear DTC operation on the scan tool (if the on-demand test shows the fault corrected). The module never resets the fault event counter to zero and continues to advance the fault event counter as short circuit fault events occur.

If the number of short circuit fault events reach the third level, then DTCs B106F and B1342 set along with the associated continuous DTC. This DTC cannot be cleared and the module must be replaced.

The SJB FET protected output circuits for the interior lighting system are the interior courtesy lamp and puddle lamp output circuits.

The Interior Lighting Control Module (ILCM) operates in a similar manner. The ILCM FET protected output circuits for the ambient lighting system are the ambient lighting output circuits.