Principles of Operation

PRINCIPLES OF OPERATION

The smart junction box (SJB) supplies voltage to the interior lighting system on circuit 1005 (VT/OG). The SJB also provides ground for the courtesy lights through circuit 401 (PK). The ground circuit for the demand lights is through circuit 57 (BK). The interior lighting system illuminates the interior lamps to enhance visibility of the interior while a vehicle door is open or ajar, and the vehicle speed is lower than 15 km/h (9 mph). The SJB controls all interior lighting functions and timing by monitoring inputs from the door ajar switches, liftgate ajar switch, liftgate glass ajar switch and vehicle speed.

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. A continuous diagnostic trouble code (DTC) is stored at that time for the fault. The circuit will then reset after an ignition cycle or customer demand of the function (switching the component on, 30-minute battery saver being energized). When an excessive circuit load occurs several times, the module shuts down the output until a service procedure is performed. At the same time, the continuous DTC that was stored on the first failure will not clear by a command to clear the continuous DTCs. The module will 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 will have been cleared and the circuit function will return.

Interior Lighting Delay
The purpose of the interior lighting delay feature is to provide temporary illumination of the interior lamps after doors are opened, then closed. The interior lighting delay feature will keep the interior lamps on for a period of up to 25 seconds, or until the ignition cycles from OFF, or the vehicle is locked using the remote keyless entry (RKE) transmitter.

Illuminated Entry
The illuminated entry requests the interior lamps to be illuminated when the ignition is OFF and the RKE transmitter unlock button is pressed. The illuminated entry requests the interior lamps off after 25 seconds elapse, the ignition is switched to ON, or when the RKE transmitter lock is pressed.

Illuminated Exit
The illuminated exit requests the interior lamps be illuminated for 25 seconds when all doors are closed and the ignition key is removed from the ignition lock cylinder. The illuminated exit will request the interior lamps be deactivated when any door becomes ajar, the key is inserted into the ignition lock cylinder, or 25 seconds elapse.

Theater Lighting
The theater lighting option ramps up the interior lamps over 0.7 seconds when interior lamp activation is requested. The theater lighting feature ramps down the interior lamps over 1.7 seconds when interior lighting deactivation is requested by any other feature other than the panic alarm or battery saver.

Interior Lamp Arbitrator
The interior lamp arbitrator (located in 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.

Battery Saver
The battery saver is internal to the SJB and provides automatic shutoff of the demand lamps (vanity lamps and map lamps) and interior 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 is started when the ignition key is turned to the OFF position. When the time-out period for the lamps has elapsed, the voltage is automatically shutoff to the lamps by the battery saver. While battery saver has voltage disabled, if the ignition is turned to any position other than OFF, any door or liftgate becomes ajar or the unlock button of the remote transmitter is pressed, the battery saver will restore voltage and start the timer again. The amount of time that is required to elapse before the voltage to the lamps is shutoff is 30 minutes (10 minutes if the lights are on due to a door ajar).