Principles of Operation

Interior Lighting

Principles of Operation

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

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 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

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 courtesy lamp off when:

- 25 seconds have elapsed
- the ignition transitions out of the OFF position
- 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 manually using the instrument panel dimmer switch (on-demand).

The demand lamp consists of the:

- 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 to 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
- Door ajar switches
- Any request from the RKE transmitter

The output is:

- Interior lamp relay