Note. The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).
The interior lighting system consists of the following
- Interior lamp
- Instrument panel dimmer switch
- Door ajar switch (located on both the front and rear door latches)
- Smart Junction Box (SJB)
Principles of Operation
Note. The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).
When the SJB detects a request for lighting, it turns on the interior lamp by supplying power to the lamp. The request for lighting can be a signal from a door ajar switch or the instrument panel dimmer switch or an unlock command from a Remote Keyless Entry (RKE) transmitter. The door ajar switches are normally open when the doors are closed. All door ajar switches receive a voltage signal from the SJB and each has its own ground circuit. The instrument panel dimmer switch receives a voltage signal from the SJB and has its own ground circuit. The instrument panel dimmer switch provides variable resistance for backlighting the Instrument Cluster (IC) and a toggle on/off function for the interior lamp.
The SJB controls the interior courtesy lamps through the interior lamp relay (internal to the SJB ).
The inputs are
- Ignition switch position
- Door ajar switches
- RKE unlock signal
The output is
- Interior lamp relay
Normal Operation
Voltage is supplied to the Smart Junction Box (SJB). The SJB fuse 13 (15A) supplies voltage to the interior lamp relay (internal to the SJB ). When any door is opened, the door ajar switch closes, signaling the SJB . The SJB monitors the door ajar circuits and the instrument panel dimmer switch input. Based on these inputs, the SJB supplies voltage to the interior lamp.
This pinpoint test is intended to diagnose the following
- Fuse
- Wiring, terminals or connectors
- Interior lamp
- SJB
When any door is opened, the door ajar switch closes, signaling the Smart Junction Box (SJB). The SJB monitors the door ajar circuits and the instrument panel dimmer switch input. Based on these inputs, the SJB supplies voltage to the interior lamp.
| DTC Description | Fault Trigger Conditions |
|---|---|
| B1322 - Driver Door Ajar Circuit Short to Ground | An on-demand DTC that sets when the SJB detects a short to ground from the LH front door ajar circuit. |
| B1330 - Passenger Door Ajar Circuit Short to Ground | An on-demand DTC that sets when the SJB detects a short to ground from the RH front door ajar circuit. |
| B1338 - Door Ajar RR Circuit Short to Ground | An on-demand DTC that sets when the SJB detects a short to ground from the RH rear door ajar circuit. |
| B1574 - Door Ajar LR Circuit Short to Ground | An on-demand DTC that sets when the SJB detects a short to ground from the LH rear door ajar 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 dimmer switch input circuit. |
FAULT TRIGGER CONDITIONS
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- 4X4 control module
- Instrument Cluster (IC)
- Door ajar switch
- SJB
When any door is opened, the door ajar switch closes and signals the Smart Junction Box (SJB). The SJB receives the door open signal and activates the interior lamp relay (internal to the SJB ) and supplies voltage to the interior lamp.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Door ajar switch
- SJB
The illuminated entry provides interior lighting when the Smart Junction Box (SJB) receives an UNLOCK request from the Remote Keyless Entry (RKE) transmitter. When the SJB receives the RKE signal, it activates the interior lamp relay (internal to the SJB ) and applies voltage to the interior lamp.
This pinpoint test is intended to diagnose the following
- RKE system
- SJB
The instrument panel dimmer switch controls the demand lighting function. The Smart Junction Box (SJB) provides a voltage signal to the instrument panel dimmer switch. When the instrument panel dimmer switch is in the DOME LAMP position, the instrument panel dimmer switch routes the voltage signal to ground. The SJB monitors the instrument panel dimmer switch circuit, and based on the status, the SJB supplies voltage to the interior lamp. The interior lamp relay in the SJB deactivates the voltage after a predetermined time-out or if turned off from the instrument panel dimmer switch.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Instrument panel dimmer switch
- SJB