Description And Operation: Description

The exterior lighting system for this vehicle includes the following exterior lamp units:

• Center High Mounted Stop Lamp  - A standard equipment Center High Mounted Stop Lamp (CHMSL) is located in the upper left rear cargo door.
• Front Fog Lamps  - Optional front fog lamp units are mounted near each outboard end of the front fascia, below the front lamp units and outboard of the lower fresh air intake.
• Headlamps  - A standard equipment front headlamp unit is mounted to the front end sheet metal outboard of each of the front fascia grille openings.
• License Plate Lamps  - Two standard equipment rear license plate lamp units are integral to the light bar and handle assembly, just above the license plate tub formation in the outer liftgate panel.
• Rear Lamp Units  - A standard equipment rear lamp unit is mounted to the rear of each quarter panel on either side of the rear cargo door opening.
• Repeater Lamps  - A repeater lamp is mounted to each front fender just behind the front wheel opening.
• Side Marker Lamps  - A side marker lamp is integral to the front fascia forward of each front wheel opening and to the rear fascia behind each rear wheel opening.

These exterior lighting lamp units and their controls are combined to provide the following exterior lighting features:

• Backup Lamps  - In vehicles manufactured for sale in markets where rear fog lamps are not required, the backup (or reverse) lamps include a clear bulb, reflector and clear lens that are integral to each rear lamp unit. Vehicles manufactured for markets where rear fog lamps are required have a clear bulb, reflector and clear lens in only the right rear lamp unit, while that same cavity in the left rear lamp unit houses the rear fog lamp behind a red lens.
• Brake Lamps  - The brake (or stop) lamps include a clear bulb, reflector and red lens that are integral to each rear lamp unit, and the red lens and multiple clear bulbs of the CHMSL.
• Daytime Running Lamps  - Daytime Running Lamps (DRL) are standard equipment. When DRL is enabled, the lamps illuminate the clearance (front position or park) lamp bulb in the front combination lamp unit to serve as the DRL. The DRL function can be turned on or off using the Electronic Vehicle Information Center (EVIC) display menus.
• Front Fog Lamps  - The optional equipment front fog lamps include the clear bulb, reflector and clear lens of each adjustable front fog lamp unit.
• Hazard Warning Lamps  - The hazard warning lamps include the bulbs, reflectors and lenses of each lamp in the right and left, front and rear turn signal circuits.
• Headlamp Delay  - Also known as the Follow Me Home feature. The standard equipment low beam headlamps and front clearance (position or park) lamps are illuminated for a customer-selected delay period when the left (lighting) multi-function switch control stalk is pulled toward the steering wheel and released within two minutes after the ignition switch has been turned to the OFF position.
• Headlamps  - The headlamps include a single halogen bulb, a shutter mechanism, a shutter solenoid and a clear, adjustable projector lens integral to each headlamp unit. The electric solenoid motor and mechanism internal to the headlamp unit closes the shutter for low beams and opens the shutter for high beams.
• Optical Horn  - Also known as flash-to-pass, the left (lighting) multi-function switch control stalk has a momentary rearward position that allows the headlamp high beams to be flashed momentarily, without changing the headlamp beam selection.
• Park Lamps  - The front park (also known as clearance or position) lamps include the clear bulbs, reflectors and clear lenses integral to the front combination lamp unit. The rear park (tail) lamps include the clear bulbs, reflectors and red lenses integral to each rear lamp unit.
• Turn Signal Lamps  - The front turn signal lamps include the amber bulbs, reflectors and clear lenses that are integral to the combination lamp unit. The amber bulbs and clear lenses of the repeater lamps on each front fender are also included in the front turn signal circuits. The rear turn signal lamps include an amber bulb, a reflector and a clear lens that is integral to each rear lamp unit.

Other components of the exterior lighting system for this vehicle include:

• Backup Lamp Switch  - On vehicles with a manual transmission, a plunger-type backup lamp switch is actuated by the shifter mechanism within the transmission when REVERSE gear is selected. On vehicles with an optional automatic transmission a stand-alone Transmission Range Sensor (TRS) performs the backup lamp switch function.
• Body Control Module  - The Body Control Module (BCM) is located beneath the instrument panel to the left of the steering column in the passenger compartment.
• Brake Lamp Switch  - A plunger-type brake lamp switch is located on the brake pedal support bracket under the instrument panel and is actuated by the brake pedal arm when the brake pedal is depressed.
• Clockspring  - The clockspring includes an integral turn signal cancel cam and both the left (lighting) and right (wiper) multi-function switches. The clockspring is located near the top of the steering column, directly beneath the steering wheel.
• Fog Lamp Switch  - Vehicles equipped with optional front or both front and rear fog lamps have a momentary fog lamp switch integral to the lower instrument panel switch pod located in the lower center of the instrument panel heater and air conditioner control head.
• Hazard Switch  - A momentary push button-actuated hazard switch is integral to the upper instrument panel switch pod located in the center of the instrument panel just below the radio and above the heater and air conditioner controls.
• Instrument Panel Cluster  - The Instrument Panel Cluster (IPC) is located in the instrument panel above the steering column opening, directly in front of the driver.
• Instrument Panel Switch Pod  - A momentary push button-actuated hazard switch is integral to the upper instrument panel switch pod located in the center of the instrument panel just below the radio. Vehicles equipped with optional fog lamps have a momentary fog lamp switch integral to the lower instrument panel switch pod located in the lower center of the instrument panel heater and air conditioner control head.
• Left Multi-Function Switch  - The left (lighting) multi-function switch is integral to the clockspring located on the steering column, just below the steering wheel. A control stalk that extends from the left side of the switch is used to select the turn signal lamps (right or left) and to select the headlamp beam (low, high or optical horn). A control knob on the control stalk is used to turn the exterior lighting ON or OFF.
• Park Brake Switch  - A park brake switch is located on the park brake lever mechanism on the floor panel transmission tunnel between the two front seats.

Hard wired circuitry connects the exterior lighting system components to the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the exterior lighting components through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators. Refer to the appropriate wiring information. The wiring information includes appropriate SYSTEM WIRING DIAGRAMS, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.

OPERATION 

Following are paragraphs that briefly describe the operation of each of the major exterior lighting systems. The lamps and the hardwired circuits between components related to the exterior lighting system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes appropriate SYSTEM 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 exterior lighting system or the electronic controls or communication between modules and other devices that provide some features of the exterior lighting system. The most reliable, efficient, and accurate means to diagnose the exterior lighting system or the electronic controls and communication related to exterior lighting system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

BACKUP LAMPS  - The backup (or reverse) lamps have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured by a ground screw to the body sheet metal. On vehicles with a manual transmission, when REVERSE is selected, the backup lamp switch provides a hardwired input to the Powertrain Control Module (PCM) through a reverse switch signal circuit. The PCM then sends an electronic reverse transmission gear selector status message to the Body Control Module (BCM) over the Controller Area Network (CAN) data bus. The BCM energizes a high side driver which provides battery voltage to the backup lamps on the backup lamp feed circuit whenever the ignition switch is in the ON position and the REVERSE position is selected with the transmission shift linkage.

On vehicles with an automatic transmission, the Transmission Control Module (TCM) monitors a multiplex input from the Transmission Range Sensor (TRS). When REVERSE is selected, the TCM sends an electronic reverse transmission gear selector status message to other electronic modules over the CAN data bus. Whenever the ignition switch is in the ON position and the BCM receives an electronic message indicating the status of the transmission gear selector is REVERSE, the BCM energizes a high side driver, which provides battery voltage to the backup lamps on the backup lamp feed circuit.

BRAKE LAMPS  - The brake (or stop) lamps and the Center High Mounted Stop Lamp (CHMSL) each have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured by a screw to the body sheet metal. The BCM receives a battery voltage input whenever the brake lamp switch is closed by the brake pedal arm. The BCM then energizes a high side driver, which provides battery voltage to the brake lamps and the CHMSL through a tail/stop lamp rear feed circuits.

DAYTIME RUNNING LAMPS  - Vehicles with the Daytime Running Lamps (DRL) feature enabled illuminate the clearance (position) lamp bulbs in the upper cavity of the two lower front combination lamp units when the engine is running, the parking brake is released, the headlamps are turned OFF, and the optional automatic transmission gear selector lever is in any position except PARK. The park lamps may be ON or OFF for DRL to operate. For vehicles with a manual transmission, the DRL will operate in any transmission gear selector lever position. The BCM must be programmed appropriately for this feature to be enabled.

Once enabled, anytime the BCM receives an electronic message input over the CAN data bus from the PCM indicating the engine is running, hardwired inputs indicating the left (lighting) multifunction switch is in any position except headlamps ON and the parking brake lever is released, and from the TCM indicating the automatic transmission gear selector lever is in any position except PARK, the BCM energizes a high side driver, which provides battery voltage to the clearance lamp bulbs through the right and left clearance lamp feed circuits.

FOG LAMPS  - The front fog lamps have a path to ground at all times through their connection to the headlamp and dash wire harness. The engine compartment wire harness has takeouts with eyelet terminals that are secured by screws to the front-end sheet metal within the engine compartment. The BCM monitors a hardwired input from the fog lamp switch in the lower instrument panel switch pod to determine whether the front fog lamps are selected. If the front fog lamps are selected and the left (lighting) multifunction switch inputs indicate the headlamp low beams are ON, the BCM energizes a high side driver, which provides battery voltage to the front fog lamps through the right and left front fog lamp feed circuits.

The BCM also sends the appropriate electronic messages to the Instrument Panel Cluster (IPC) over the CAN data bus to illuminate or extinguish the front fog lamp indicator. The BCM will automatically de-energize the front fog lamps any time the headlamps are turned OFF or the headlamp high beams are selected.

Each front fog lamp includes an integral adjustment screw to be used for static aiming of the fog lamp beams.

HAZARD WARNING LAMPS  - The BCM monitors a hardwired input from the hazard switch in the lower instrument panel switch pod located in the center of the air conditioner and heater control head to determine whether the hazard warning system has been selected. When the hazard warning system is selected, the BCM controls hazard warning system operation and flash rate by energizing and de-energizing high side drivers, which controls battery voltage outputs on the right and left turn signal feed circuits. The BCM also sends electronic hazard switch status  messages to the IPC over the CAN data bus to control the illumination and flash rate of the left and right turn signal indicators, as well as to control the click rate of an electromechanical relay soldered onto the IPC electronic circuit board that emulates the sound emitted by a conventional hazard warning flasher.

HEADLAMPS  - The headlamp system includes the BCM, the IPC and the left (lighting) multifunction switch on the steering column. The headlamp bulbs have a path to ground at all times through their connection to the headlamp and dash wire harness. The headlamp and dash wire harness has takeouts with eyelet terminals that are secured by screws to the front-end sheet metal within the engine compartment. The BCM monitors hardwired inputs to determine the status of the left multifunction switch and whether the headlamp high or low beams are selected. The BCM then controls headlamp illumination through relays soldered onto the BCM internal circuit board.

When the BCM detects a change in headlamp beam selection, the BCM energizes or de-energizes a high side driver, which controls an output to the solenoid that operates the shutter in each headlamp. The BCM also sends the appropriate electronic messages to the IPC to control the illumination of the high beam indicator. The BCM remembers which beams (LOW or HIGH) were selected when the headlamps were last turned OFF and energizes those beams again the next time the headlamps are turned ON.

Each headlamp includes an integral reflector adjustment screw to be used for static aiming of the headlamps.

HEADLAMP DELAY  - The headlamp delay feature (also known as the Follow Me Home feature) includes the left (lighting) multifunction switch, the IPC and the BCM. The BCM controls this feature by monitoring inputs from the ignition switch and the left (lighting) multifunction switch. If within two minutes after the ignition switch is turned to the OFF position, the left multifunction switch control stalk is pulled toward the steering wheel and released the BCM energizes the relay that controls the headlamp low beams and the high side driver that controls the clearance (position) lamps for 30 seconds. Each additional activation of the control stalk extends the delay by 30 seconds, up to a maximum of 210 seconds. The BCM automatically de-energizes the lamps after the selected time interval expires or, immediately, if the control stalk is pulled toward the steering wheel and held for more than two seconds. The BCM also sends the appropriate electronic messages to the IPC over the CAN data bus to control the Follow Me Home indications in the IPC display.

PARK LAMPS  - The park lamps system includes the left (lighting) multifunction switch, the IPC and the BCM. The clearance (position) lamp bulbs in the upper cavity of each lower front combination lamp unit have a path to ground at all times through their connection to the headlamp and dash wire harness. The headlamp and dash wire harness has takeouts with eyelet terminals that are secured by screws to the front-end sheet metal within the engine compartment. The park (tail) lamp bulbs in each rear lamp unit and the license plate lamps have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured by a screw to the body sheet metal within the passenger compartment.

The BCM monitors a hardwired input from the left (lighting) multifunction switch, then responds to this input by energizing or de-energizing high side drivers, which control battery voltage outputs to the appropriate lamps and bulbs through the proper park/tail/license/running lamp right and left circuits. The BCM also provides the appropriate electronic messages to the IPC to control the illumination and lighting level of the panel lamps.

TURN SIGNAL LAMPS  - The turn signal lamps system includes the left (lighting) multifunction switch, the IPC and the BCM. The front turn signal lamp bulbs in the lower cavity of each lower front combination lamp unit. The rear turn signal lamp bulbs have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured by a screw to the body sheet metal within the passenger compartment.

The BCM monitors a hardwired input from the left (lighting) multifunction switch to determine the status of the turn signal switch, then controls turn signal operation and flash rate by energizing and de-energizing high side drivers, which control battery voltage outputs on the right or left turn signal feed circuits. The BCM also sends electronic turn signal switch status messages to the IPC over the CAN data bus to control the illumination and flash rate of the left or right turn signal indicators, as well as to control the click rate of an electromechanical relay soldered onto the IPC electronic circuit board that emulates the sound emitted by a conventional turn signal flasher.