Principles of Operation

Interior Lighting

Principles of Operation

This vehicle uses a Lighting Control Module (LCM) to control lighting functions. The LCM is a microprocessor-based module that controls several vehicle subsystems, responds to electrical input signals from various switches, sensors, and external modules and is located on the LH side of the instrument panel.

The LCM interfaces with the Driver Door Module (DDM) via the Standard Corporate Protocol (SCP) network for the illuminated entry feature.

A theater lighting feature gradually increases or decreases the light intensity when opening or closing a door.

The courtesy lamps (controlled by the LCM) are activated by using the dome lamp switch (instant on/off response) or when a door is ajar. The following lamps illuminate for courtesy lighting:

- Front footwell lamps
- Front map lamps
- Rear reading lamps
- Door lamps

The courtesy lamps can also be illuminated by moving the instrument panel dimmer switch to the RH position until the dome lamps turn on.

Demand lighting includes lamps that are illuminated by directly actuating a switch. The front dome/map lamps are located in the overhead console. Each lamp is controlled by its own switch.

Both subsystems use the same power supply circuit through the Central Junction Box (CJB) fuse 18 (15A).

The following demand lamps are powered by the demand lighting output of the LCM:

- Glove compartment lamp
- Vanity mirror lamp
- Luggage compartment lamp
- Front map lamps
- Rear reading lamps

Each lamp has a dedicated switch that closes to ground to illuminate the lamp.

The luggage compartment lamp is controlled by input from the luggage compartment ajar switch, and is powered by the demand lighting output from the LCM, and is mounted near the center of the upper rear panel.

The battery saver feature prevents excessive drain from loads inadvertently left on. When the ignition switch is turned off, power is interrupted to the courtesy lamps (after a 10 minute timeout) and the demand lamps (after a 30 minute timeout).

The battery saver has the following inputs:

- Luggage compartment lid ajar switch
- Dome lamp switch
- Ignition switch status
- Illuminated entry signal
- Headlamp switch
- Driver/passenger door ajar entry switch
- RKE transmitter
- Door unlock, luggage compartment door release

The battery saver has the following outputs:

- Courtesy lamps
- Headlamps
- Demand lamps

When the ignition switch is turned to off, the courtesy lamps interrupt timer, and the demand lamps interrupt timer begin their timeout. The interrupt timer is a feature of the LCM. Power is available to the courtesy lamps, headlamps, and demand lamps during timeout. At the end of the 10 (± 1) minute timeout period, the LCM disables power to the courtesy lamps. At the end of the 30 minute timeout period, the LCM disables power to the demand lamps. If the dome switch is causing the courtesy lamps to be on, then timeout is 30 minutes. Turning the ignition switch to the ACC or RUN position terminates the battery saver feature by disabling the interrupt timers and reinstating power to the lamps.

A reset event sets the courtesy lamps interrupt timer to zero. The reset events for the courtesy lamps and the demand lamps interrupt timer are as follows:

- Turning on the courtesy lamps using the dome lamp switch
- Opening any door (as detected by the door ajar lamp switches)
- Luggage compartment lid ajar
- Any RKE transmitter button pressed
- Headlamp switch change to PARKING or HEADLAMPS ON position

When the PANIC button is pressed on a RKE transmitter, the panic alarm overrides the courtesy lamps, demand lamps and headlamps battery saver functions for the duration of the alarm.