Description And Operation

DESCRIPTION 

The interior lamps and lighting system include the following components and features:

Ambient Lighting -  The vehicle is equipped with numerous ambient lamps to illuminate all the interior. The brightness of instrument lamps can be adjusted by a button on the slide of the light switch.

Dome Lamps -  Front seat driver side and passenger side dome lamps and a central dome lamp with dedicated control buttons, the buttons can be used to illuminate the corresponding lamp directly or in a timed manner following door opening/closing. The rear central dome lamp switch is also housed in the front dome lamp.

Door Entry And Exit Lamps -  Door entry and exit lamps (also known as puddle lamps) include an incandescent lamp unit on the underside of each door trim panel that illuminate the ground outside the opened doors to assist visibility at night. These lamps are controlled by the courtesy lamps circuit and illuminate whenever the door is opened.

Glove Box Lamp -  A standard glove box lamp with an integral plunger-actuated switch is located at the upper outboard corner of the instrument panel lower glove box opening and illuminates whenever the glove box door is opened.

Instrument Lighting -  The vehicle is equipped with numerous lamp and lighting sources for illumination of interior instruments and controls. The brightness of instrument lamps can be adjusted by a button on the slide of the light switch.

Trunk Lamps -  Standard trunk lamps are located in the right and left trunk trim panels and are activated automatically whenever the deck lid is opened to illuminate the trunk of the vehicle.

Vanity Lamps -  Optional single-intensity vanity lamps are located on both sides of a covered mirror on both the right and left sun visors. These lamps are controlled by an integral vanity mirror cover-actuated switch.

Other components of the interior lighting system for this vehicle include.

• Body Control Module -  The Body Control Module (BCM) is located beneath the instrument panel on the passenger side of the vehicle. Refer to MODULE, BODY CONTROL (BCM), DESCRIPTION AND OPERATION .
• Dimmer Module -  A dimmer module is located on the left side of the instrument panel, below and outboard of the steering column just inboard from the headlamp switch. The dimmer module features a vertical thumbwheel for selecting the panel lamps dimming level, a PARADE mode to illuminate all Vacuum Fluorescent Display (VFD) units at full brightness for visibility when driving in daylight with the exterior lighting turned ON. There are also detent positions to turn ON all interior courtesy lighting, and a DEFEAT position that overrides door ajar switch control of interior lighting. On vehicles equipped with the ambient lighting option the dimmer module includes a second thumbwheel dedicated to the ambient lighting, which allows the selection of the ambient lighting dimming level while the exterior lighting is turned ON and includes a detent position that turns the ambient lighting OFF
• Door Ajar Switches -  A door ajar switch is integral to the door latch mechanism of each door.
• Trunk Ajar Switch -  A trunk ajar switch is integral to the deck lid latch mechanism.

OPERATION 

All internal lights are powered by the Inadvertent Lighting Feed. That inadvertent Lighting Feed is controlled via the SBMT Relay located in the BCM.

The lamps and the hard wired circuits between components related to the interior lighting system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the interior lighting system or the electronic controls or communication between modules and other devices that provide some features of the interior lighting system. The most reliable, efficient, and accurate means to diagnose the interior lighting system or the electronic controls and communication related to interior lighting system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

Ambient Lighting 

The ambient lighting functions includes several components and circuits. These circuits control the overhead flood light, front remote handles, front map pockets, rear remote handles, pass through bin lighting, back lighting illumination and dimming level of the headlamp switch, the dimmer module, and the automatic transmission gear selector bezel lamp. Power for the Ambient Lighting Functions are sourced via the Internal Lights Power Feed from the BCM. All ambient lamps on these circuits are provided a path to ground at all times through a hard wired ground circuit. These lamps are illuminated by a 12-volt Pulse Width Modulated (PWM) output of the BCM through several panel lamps dimmer circuits.

This shared PWM output synchronizes the selected illumination intensity level of all the lamps in the panel lamps dimmer circuits. The BCM uses hard wired resistor multiplexed inputs from the rotary exterior lighting control knob of the headlamp switch to determine when the exterior lighting is turned ON and from the thumbwheel of the dimmer module to determine the dimming level selection. Then the BCM provides the appropriate PWM outputs through the panel lamps dimmer circuits as well as electronic dimming level messages over the CAN data bus to other electronic modules in the vehicle.

The IPC and the Integrated Center Stack (ICS) use the electronic dimming level messages to control the illumination intensity of their own back lighting, controls and display units. In addition, when the interior lighting thumbwheel of the dimmer module is moved to the PARADE (or funeral) mode detent position, all of the electronic display units are illuminated at their full intensity levels for increased visibility when the vehicle is driven during daylight hours with the exterior lighting turned ON. The PARADE mode has no effect on the illumination intensity of incandescent panel lamps.

The BCM provides power through a fuse protected line to the courtesy lights, and ground is also provided through the BCM.

The BCM sends a signal to the IPC to illuminate the door open warning light and activate the buzzer to give an acoustic signal, where necessary.

Courtesy Lighting 

The courtesy lamp circuit includes the dome/reading lamps located on the headliner near the center of the windshield opening upper header and front courtesy footwell lamps. The lamps in the courtesy lamp circuit are provided with battery voltage and ground by the BCM using internal low side drivers through two ground circuits based upon hard wired inputs from the ignition switch and the door ajar switches. The BCM also uses electronic message inputs received from other electronic modules in the vehicle over the Controller Area Network (CAN) data bus to control these outputs

The operation of the ceiling lamps is timed according to a logic managed by the BCM which adjusts dimmed operation and switch-off according to:

• Door unlocking
• Opening of any door
• Closing of all doors
• Door locking control

The timing can be adjusted by using the Radio system settings menu. The power supply for the roof lamps follows the battery voltage control logic (SBMT): with the key function on STOP, when any door or the trunk are opened, a timed period of 15 minutes is set. After this, all the ceiling lamps are deactivated. If one or more doors are open, this is shown on the instrument panel display; the warning lamp remains illuminated until all the car's doors and luggage compartment.

When the BCM receives a "door open" signal from the door switch a ground signal is sent to the front and rear courtesy (puddle) lamps to turn the lamps on.

The BCM provides power through a fuse protected line to the courtesy lamps, and ground is also provided through the BCM.

The BCM sends a signal to the Instrument Panel Cluster (IPC) to illuminate the door open warning lamps and activate the buzzer to give an acoustic signal, where necessary.

Ambient Lighting 

The ambient lighting functions includes several components and circuits. These circuits control the overhead flood light, front remote handles, front map pockets, rear remote handles, pass through bin lighting, back lighting illumination and dimming level of the headlamp switch, the dimmer module, and the automatic transmission gear selector bezel lamp. Power for the Ambient Lighting Functions are sourced via the Internal Lights Power Feed from the BCM. All ambient lamps on these circuits are provided a path to ground at all times through a hard wired ground circuit. These lamps are illuminated by a 12-volt Pulse Width Modulated (PWM) output of the BCM through several panel lamps dimmer circuits.

This shared PWM output synchronizes the selected illumination intensity level of all the lamps in the panel lamps dimmer circuits. The BCM uses hard wired resistor multiplexed inputs from the rotary exterior lighting control knob of the headlamp switch to determine when the exterior lighting is turned ON and from the thumbwheel of the dimmer module to determine the dimming level selection. Then the BCM provides the appropriate PWM outputs through the panel lamps dimmer circuits as well as electronic dimming level messages over the CAN data bus to other electronic modules in the vehicle.

The IPC and the Integrated Center Stack (ICS) use the electronic dimming level messages to control the illumination intensity of their own back lighting, controls and display units. In addition, when the interior lighting thumbwheel of the dimmer module is moved to the PARADE (or funeral) mode detent position, all of the electronic display units are illuminated at their full intensity levels for increased visibility when the vehicle is driven during daylight hours with the exterior lighting turned ON. The PARADE mode has no effect on the illumination intensity of incandescent panel lamps.

The BCM will receive a dimming signal from the dimming module, and will resend the signal to the following components:

• IPC
• Hazard warning lights switch
• The AUX, USB, and power outlet lamps
• Controls on the dome lamps
• Rear dome lamps
• The courtesy lamps on the doors
• Trunk opening button
• Electric brake switch
• DNA switch

The BCM provides power through a fuse protected line to the courtesy lights, and ground is also provided through the BCM.

The BCM sends a signal to the IPC to illuminate the door open warning light and activate the buzzer to give an acoustic signal, where necessary.

Trunk Lamps 

The trunk switch sends a ground signal to the BCM to signal the trunk lamps to turn on.

Vanity Lamps 

The vanity lamps are switched on by a ground signal from the switch on the light cover.