Principles of Operation

PRINCIPLES OF OPERATION

The interior lighting can be separated into 2 distinct modes of operation:
- Interior lighting
- Demand lighting

The lighting control module (LCM) controls all of the interior lighting in the vehicle.

Lighting Control Module (LCM)
This vehicle uses an 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 subsystem functions include:
- Headlamps with autolamps
- Turn signal lamps/hazard flasher lamps
- Cornering lamps
- Parking lamps
- Daytime running lamps (DRL)
- Fog lamps
- Interior lamps
- Demand lamps
- Battery saver

The LCM interfaces with the driver door module (DDM) via the standard corporate protocol (SCP) network for the illuminated entry feature.

The interior lamp is illuminated by pressing the individual interior lamp switch. The interior lamp is also illuminated by door ajar switches located in the door latches, when any door is opened. A theater lighting feature gradually changes the light intensity when switched by opening or closing a door.

The dome/map lamp combination is located on each side of the interior lamp. The map lamps are operated independently of the interior lamp by 2 switches located on the interior lamps.

The interior lamps are also illuminated by moving the instrument panel dimmer switch to the RH position until the dome lamps turn on.

The front map lamps are powered by the demand lighting circuit and the interior lighting circuit.

The rear passenger reading lamps are incorporated into the headliner. These lamps are illuminated through power supplied by the LCM demand lighting circuit.

Interior 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 interior lighting:
- Front footwell lamps
- Front map lamps
- Rear reading lamps

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

The following demand lamps are powered by the demand lighting output of the LCM:
- Glove compartment lamp
- Vanity mirror lamps
- Luggage compartment lamp
- Rear reading lamps
- Front map lamps
- Red/White map lamp (Police if equipped)

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

The front map lamps are powered by either the demand lighting circuit or the interior lighting circuit, depending upon the position of the switch associated with each lamp. When the customer turns the front map lamp switch on, the front map lamp is illuminated through power supplied by the LCM demand lighting circuit. If the customer moves the map lamp switch to the OFF position, the power from the LCM demand lighting circuit is interrupted and the lamp is reconnected to the interior lighting circuit.

The rear reading lamps are powered by either the interior lighting circuit or the demand lighting circuit.

The luggage compartment lamp is controlled by input from the trunk 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 glove compartment lamp system consists of a glove compartment lamp switch and wire and miniature bulb assembly. Opening the glove compartment door closes the switch which provides power to the glove compartment lamp switch and wire. The glove compartment lamp switch is grounded to the body sheet metal.

The vanity mirror lamp system consists of a switch and bulb assembly in the RH inside visor and the LH inside visor. Lifting the vanity mirror cover closes the vanity mirror lamp switch and provides power to the lamps.

The illuminated entry system is controlled by the LCM and provides interior lighting upon entry to the vehicle.

Interior lamps illuminate for 25 (±1) seconds which includes a theater lighting ramp-up time (0.5 seconds) after the doors are closed. This time interval does not include the theater lighting ramp-down time. Interior lamps are turned off before the 25 (±1) second timeout if the ignition switch is turned to the RUN or ACC position.

The illuminated entry system has the following additions to accommodate the remote entry system:
- Pressing the unlock button on the remote keyless entry (RKE) transmitter activates the illuminated entry system (with theater ramp-up)
- When the DDM detects a button has been pressed, it sends a signal on the SCP communication network activating the interior lamps
- The LCM turns off the lamps by sensing an all doors locked signal

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

The battery saver has the following inputs:
- Luggage compartment lid door ajar switch
- Dome lamp switch
- Ignition switch status
- Illuminated entry signal
- Instrument panel dimmer switch
- Door ajar switch
- RKE transmitter
- Door unlock, luggage compartment door release

The battery saver has the following outputs:
- Interior lamps
- Headlamps
- Demand lamps

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

A reset event sets the interior lamps interrupt timer to zero. The reset events for the interior lamps and the demand lamps interrupt timer are as follows:
- Turning on the interior lamps using the dome lamp switch
- Opening any door (as detected by the door ajar switches)
- Luggage compartment lid ajar
- Any RKE transmitter button pressed
- Headlamp switch change to PARK or HEADLAMPS ON position

When the panic button is pressed on a keyless entry transmitter, the panic alarm overrides the interior lamps, demand lamps and headlamps battery saver functions for the necessary duration of the alarm.