Note. The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).
The interior lighting system consists of the following
- Door ajar switches
- Glove compartment lamp assembly
- Illuminated vanity mirrors (if equipped)
- Instrument panel dimmer switch
- Interior/map reading lamp(s)
- Liftgate ajar switch
- Liftgate glass ajar switch
- Liftgate/Trunk Module (LTM) (if equipped)
- Puddle lamps
- Rear cargo lamp
- SJB
The interior lighting system consists of 2 subsystems
- Courtesy lamps
- Demand lamps
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 while a vehicle door is open or ajar, and the vehicle speed is less than 15 km/h (9 mph) or 5 km/h (3 mph) for puddle lamps. The SJB controls all interior lighting functions and timing by monitoring inputs from the door ajar switches, the instrument panel dimmer switch, and the vehicle speed.
Normal Operation
The Smart Junction Box (SJB) sends a voltage signal to the door ajar switches to monitor each door position. When the door is closed, the voltage signal is routed to ground. When a door is opened, the signal to ground is interrupted indicating an open door to the SJB .
The SJB also monitors the courtesy dome defeat input by sending a voltage reference to the instrument panel dimmer switch. When the dome defeat is requested, the voltage signal is routed to ground. When the SJB detects this request, the courtesy lamps are not illuminated when a door (or liftgate) is opened.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Door ajar switch
- Instrument panel dimmer switch
- SJB
The Smart Junction Box (SJB) monitors the instrument panel dimmer switch status with a voltage signal to determine if the courtesy lamps are requested. When the instrument panel dimmer switch is rotated to the dome detent, the voltage signal is routed to ground. Based on the instrument panel dimmer switch status, the SJB supplies voltage to the courtesy lamps.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- SJB
The SJB sends a voltage signal to the Liftgate/Trunk Module (LTM) (vehicles with a power liftgate) or to the liftgate glass ajar switch and the liftgate ajar switch (vehicles with a manual liftgate). The voltage signal is routed to ground when the liftgate glass or liftgate are closed. When the liftgate or liftgate glass is opened, the signal to ground is interrupted, indicating an open door or liftgate.
- DTC B2721 (Liftgate/Decklid Ajar Output Short to Ground or Open) - a continuous and on-demand DTC that sets when the LTM detects a short to ground from the SJB liftgate ajar input circuit.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Liftgate ajar switch (integrated into the liftgate latch)
- Liftgate glass ajar switch (integrated into the liftgate latch)
- LTM
- SJB
The Smart Junction Box (SJB) sends a voltage signal to the instrument panel dimmer switch to monitor the dome defeat input request. When the instrument panel dimmer switch is in the DOME DEFEAT position, the signal is routed to ground indicating a request for the dome defeat feature.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- SJB
Voltage is supplied to the courtesy lamps through the Smart Junction Box (SJB) fuse 9 (15A). Based on input status from the ajar switches and the instrument panel dimmer switch, the SJB supplies voltage to the courtesy lamp(s).
| DTC Description | Fault Trigger Conditions |
|---|---|
| B106E - Solid State Driver Disabled Due to Short Circuit | A continuous DTC that sets when the SJB has temporarily shut down the output driver. The module has temporarily disabled the interior courtesy lamp output because an excessive current draw exists (such as a short to ground). The SJB cannot enable the interior courtesy lamp output until the cause of the short is corrected, the DTCs have been cleared and a successful self-test is run . |
| B106F - Module Disabled Due to External Fault | A continuous DTC that sets when the SJB has permanently shut down the output driver. The module has permanently disabled the interior courtesy lamp output because an excessive current draw fault (such as a short to ground) has exceeded the limits that the SJB can withstand. The cause of the excessive current draw MUST be corrected before a new SJB is installed . |
| B2A35 - Interior Lighting Output Circuit Open | An on-demand DTC that sets when the SJB detects an open from the courtesy lighting output circuit. |
| B2A36 - Interior Lighting Output Circuit Short To Ground | A continuous and on-demand DTC that sets when the SJB detects a short to ground from the courtesy lighting output circuit. |
DTC DESCRIPTION CHART
This pinpoint test is intended to diagnose the following
- Fuse
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- SJB
Power is supplied to the puddle lamps from the Smart Junction Box (SJB) fuse 10 (15A). Based on the input status, the SJB supplies voltage to the puddle lamps.
| DTC Description | Fault Trigger Conditions |
|---|---|
| B106E - Solid State Driver Disabled Due to Short Circuit | A continuous DTC that sets when the SJB has temporarily shut down the output driver. The module has temporarily disabled the interior courtesy lamp output because an excessive current draw exists (such as a short to ground). The SJB cannot enable the interior courtesy lamp output until the cause of the short is corrected, the DTCs have been cleared and a successful self-test is run . |
| B106F - Module Disabled Due to External Fault | A continuous DTC that sets when the SJB has permanently shut down the output driver. The module has permanently disabled the interior courtesy lamp output because an excessive current draw fault (such as a short to ground) has exceeded the limits that the SJB can withstand. The cause of the excessive current draw MUST be corrected before a new SJB is installed . |
| B2A39 - Puddle Lamp Output Circuit Open | An on-demand DTC that sets when the SJB detects an open from the puddle lamp output circuit. |
| B2A3A - Puddle Lamp Output Circuit Short To Ground | A continuous and on-demand DTC that sets when the SJB detects a short to ground from the puddle lamp output circuit. This DTC also sets as a result when the SJB fuse 10 (15A) has failed or is removed. |
DTC DESCRIPTION CHART
This pinpoint test is intended to diagnose the following
- Fuse
- Wiring, terminals or connectors
- Exterior mirror
- SJB
The Smart Junction Box (SJB) sends a voltage signal to each door ajar switch, the Liftgate/Trunk Module (LTM) (vehicles with a power liftgate), the liftgate glass ajar switch and the liftgate ajar switch (vehicles with a manual liftgate). The voltage signal is routed to ground when the door, liftgate glass or liftgate are closed. When a door, liftgate or liftgate glass is opened, the signal to ground is interrupted, indicating an open door or liftgate.
The SJB also sends a voltage signal to the instrument panel dimmer switch to monitor for a dome lamp request. When the signal is routed to ground, the SJB interprets this as a request for the courtesy lamps.
| DTC Description | Fault Trigger Conditions |
|---|---|
| B1320 - Driver Door Ajar Circuit Open | An on-demand DTC that sets when the SJB detects an open from the LH front door ajar input circuit. |
| B1328 - Passenger Door Ajar Circuit Open | An on-demand DTC that sets when the SJB detects an open from the RH front door ajar input circuit. |
| B1336 - Door Ajar RR Circuit Open | An on-demand DTC that sets when the SJB detects an open from the RH rear door ajar input circuit. |
| B1572 - Door Ajar LR Circuit Open | An on-demand DTC that sets when the SJB detects an open from the LH rear door ajar input circuit. |
| B1688 - Lamp Dome Input Circuit Short to Ground | An on-demand DTC that sets when the SJB detects a short to ground from the dome lamp request input circuit. |
| B2077 - Liftgate Ajar Sw Circuit Failure | An on-demand DTC that sets when the SJB detects an open from the liftgate glass or the liftgate ajar input circuit. |
| B2A35 - Interior Lighting Output Circuit Open | An on-demand DTC that sets when the SJB detects a short to voltage from the courtesy lamp output circuit. |
| B2718 - Liftgate/Decklid Ajar Output Short to Battery | A continuous and on-demand DTC that sets when the LTM detects a short to voltage from the SJB liftgate ajar input circuit. |
| B2721 - Liftgate/Decklid Ajar Output Short to Ground or Open | A continuous and on-demand DTC that sets when the LTM detects an open from the SJB liftgate ajar input circuit. |
| B2723 - Glass Position Switch Active During Selftest | An on-demand DTC that sets when the LTM detects an open from the liftgate glass ajar input circuit. |
DTC DESCRIPTION CHART
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- Door ajar switch
- Liftgate ajar switch (integrated into the liftgate latch)
- Liftgate glass ajar switch (integrated into the liftgate latch)
- LTM
- SJB
When the Smart Junction Box (SJB) receives a request for the courtesy lamps, the SJB provides voltage to the puddle lamps.
- DTC B2A39 (Puddle Lamp Output Circuit Open) - an on-demand DTC that sets when the SJB detects a short to voltage from the puddle lamp output circuit.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- SJB
The Smart Junction Box (SJB) supplies voltage to the demand lamps when the battery saver relay is energized.
This pinpoint test is intended to diagnose the following
- Fuse
- Wiring, terminals or connectors
- SJB
The Smart Junction Box (SJB) supplies voltage to the demand lamps when the battery saver relay is energized.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Interior lamp
The Smart Junction Box (SJB) controls the battery saver function. The battery saver function provides automatic shutoff of the interior lamps (demand lamps, and glove compartment lamp) after 10 minutes have elapsed in order to save battery power.
This pinpoint test is intended to diagnose the following
- Wiring, terminals, or connectors
- SJB