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. When the instrument panel dimmer switch is not in the DOME DEFEAT position and a vehicle door is ajar with the vehicle speed less than 15 km/h (9 mph), or the instrument panel dimmer switch is in the DOME LAMP position, the 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, liftgate and liftgate ajar switches, the instrument panel dimmer switch 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.

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, liftgate and liftgate glass are closed. When 10 minutes has elapsed, voltage is automatically shut off to the lamps by the SJB. While the SJB has voltage disabled, if the ignition is turned to any position other than OFF, any door, liftgate or liftgate glass becomes ajar, the UNLOCK button of the Remote Keyless Entry (RKE) transmitter is pressed or the instrument panel dimmer switch is rotated to the DOME LAMP position, the SJB restores voltage and starts the timer again.

Ambient Lighting

The ambient lighting feature provides illumination of the cup holders, storage tray and the storage bin in the center floor console and to the front and rear footwell areas. There are a total of 8 LED lighting locations. The ambient lighting feature is only available when the ignition key is in the RUN or ACC position.

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.

Field-Effect Transistor (FET) Protection

The SJB utilizes a Field-Effect Transistor (FET) 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 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. The next time a request activates a circuit 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 total 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), the continuous DTC 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 self-test, then the Clear DTC operation on the scan tool as long as the fault itself has been corrected.

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 circuit for the interior lighting system is the courtesy lamp output circuit.