Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Principles of Operation
Interior Lighting
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, an interior lighting on command from the instrument panel dimmer switch or an unlock command from a remote keyless entry (RKE) transmitter. The door ajar switches are hard-wired directly to the SJB. The door ajar switches are normally open when the doors are closed. All door ajar switches receives 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 and a toggle on/off function for the courtesy lamp.
The inputs are:
- Ignition switch position
- LH front door ajar switch
- RH front door ajar switch
- LH rear door ajar switch
- RH rear door ajar switch
- RKE unlock signal
For additional door ajar switch information, refer to HANDLES, LOCKS, LATCHES & ENTRY SYSTEMS article.
The output is:
- Interior lamp relay
Illuminated Entry (Option)
The illuminated entry feature requests the interior lamp on when the ignition switch is in the OFF position and the operator activates an external unlock feature (key fob). The illuminated entry feature requests the interior lamp off when: 25 seconds have elapsed, the ignition transitions out of the OFF position, or the customer activates an external lock feature.
The inputs are:
- Ignition switch position
- Unlock request from the RKE transmitter
The output is:
- Interior lamp relay
Demand Lamp
The demand lamp function can be operated independently.
The demand lamp consists of a:
- Interior lamp
- Instrument panel dimmer switch
The demand lamp is also controlled by the interior lighting arbitrator and the interior lamp relay.
Interior Lighting Arbitrator
The interior lighting arbitrator decides between the interior lighting, the illuminated entry lighting, and the battery saver features to determine which feature has precedence for turning on and off the interior light. This feature is internal in the SJB.
The output is:
- Interior lamp relay
Battery Saver
When the ignition is off, the battery saver timer feature provides timed automatic shut-off of power to the interior lamp and the warning chimes. The battery saver has a time-out period of 5 minutes. The battery saver restores power to the interior lamp or resets the 5 minute timer if any of the following interactions are detected:
- The ignition is turned to any position other than OFF.
- Any door becomes ajar.
- Any button of a RKE transmitter which provides access to the vehicle is pressed (key fob).
The inputs are:
- Ignition switch position
- LH front door ajar switch
- RH front door ajar switch
- LH rear door ajar switch
- RH rear door ajar switch
- Any request from the RKE transmitter
The output is:
- Interior lamp relay
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.