Lamps/Lighting - Exterior

The exterior lighting system for this model includes the following exterior lamps:
- Backup Lamps - The backup (or reverse) lamps are integral to the tail lamp units mounted to the back of the quarter panel on each side of the tailgate at the rear of the vehicle.
- Brake Lamps - The brake (or stop) lamps include a bulb and reflector that are integral to the tail lamp units mounted to the back of the quarter panel on each side of the tailgate opening, and the Center High Mounted Stop Lamp (CHMSL) that is centered on the rear edge of the roof panel above the tailgate opening.
- Daytime Running Lamps - Vehicles manufactured for sale in Canada have a Daytime Running Lamps (DRL) relay that illuminates the low beam headlamp bulbs whenever the engine is running.
- Fog Lamps - Fog lamp bulbs and reflectors are included in both front lamp units of vehicles equipped with this option.
- Hazard Warning Lamps - The hazard warning lamps include all of the right and left turn signal and repeater lamps.
- Headlamps - Separate low beam and high beam headlamp bulbs are installed in the front lamp unit on each side of the front grille opening. A headlamp leveling actuator motor is also integral to each front lamp unit.
- Park Lamps - The park lamps include the front park/side marker lamps and front position lamps that are integral to the front lamp units mounted on either side of the front grille opening, as well as the rear park lamps and rear side marker lamps that are integral to the tail lamp units mounted to the back of the quarter panel on each side of the tailgate opening. Included in the park lamps circuit are two rear license plate lamp units mounted on the left rear tailgate door. The park lamps may also include optional clearance lamps, which are located on each side of a vehicle that is so equipped.
- Turn Signal Lamps - The turn signal lamps include the front turn lamps that are integral to the front lamp units, the rear turn lamps that are integral to the tail lamp units, and a repeater lamp mounted to each front fender just above the front wheel opening.
Other components of the exterior lighting system for this model include:
- Brake Lamp Switch - A plunger-type brake lamp switch is located on the steering column support bracket under the instrument panel and actuated by the brake pedal arm.
- Daytime Running Lamp Relays - Vehicles manufactured for sale in Canada have two Daytime Running Lamps (DRL) relays. Dedicated right and left side relays illuminate the low beam headlamp bulb installed in each front lamp unit whenever the engine is running. These relays are located in dedicated vehicle wire harness connectors within the driver side front seat riser.
- Fog Lamp Relay - Vehicles equipped with the optional fog lamps have a fog lamp relay located in a dedicated vehicle wire harness connector within the driver side front seat riser.
- Fog Lamp Switch - A fog lamp switch is mounted in the instrument cluster bezel, below the cluster and outboard of the steering column on vehicles equipped with this option.
- Headlamp Leveling Motor -A headlamp leveling actuator motor is located on the back of each headlamp housing and adjusts both the low beam headlamp, high beam headlamp, and fog lamp (if equipped) reflector frames in unison.
- Headlamp Leveling Switch - A thumb wheel actuated headlamp leveling switch is mounted in the instrument cluster bezel, below the cluster and outboard of the steering column.
- Multi-Function Switch - The multi-function switch is located on the top of the steering column, just below the steering wheel. The multi-function switch is connected directly to the fuse block located below the steering column through an integral interface connector. Only the left (lighting), right (wiper) control stalks and the hazard warning switch button for the multi-function switch are visible, the remainder of the switch is concealed beneath the steering column shrouds. The multi-function switch includes a left (lighting) control stalk and a right (wiper) control stalk. The left control stalk is dedicated to providing almost all of the driver controls for the exterior lighting system.
- Trailer Tow Connector - Vehicles equipped with a factory-approved, field-installed trailer towing electrical package have a heavy duty 7-way trailer tow connector installed in a bracket on the trailer hitch receiver. This package includes a 7-way to 4-way connector adapter unit.
- Trailer Tow Control Module - Vehicles equipped with a factory-approved, field-installed trailer towing electrical package have a trailer tow brake/turn control module located within the driver side front seat riser that controls the brake lamp and turn signal lamp outputs to the trailer lighting circuits.
- Turn Signal Relay - A turn signal relay is installed in the fuse block located on the underside of the steering column behind a fuse access panel in the steering column opening cover on the instrument panel. The electronic circuitry of the wipers, turn signals and engine start control module within the fuse block controls the turn signal relay.
- Wipers, Turn Signals, Engine Start Control Module - The wipers, turn signals and engine start control module is integral to the fuse block located on the underside of the steering column behind a fuse access panel in the steering column opening cover on the instrument panel. This module includes active electronic elements that control the operation of the turn signal relay based upon inputs from the multifunction switch and feedback from the turn signal circuits.

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 system 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 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.

Following are paragraphs that briefly describe the operation of each of the major exterior lighting systems. The hard wired circuits and components of the exterior lighting systems may be diagnosed and tested using conventional diagnostic tools and procedures. However, conventional diagnostic methods may not prove conclusive in the diagnosis of the wipers, turn signals and engine start control module located within the fuse block underneath the steering column, the ElectroMechanical Instrument Cluster (EMIC), the Engine Control Module (ECM), or the Controller Area Network (CAN) data bus network. The most reliable, efficient, and accurate means to diagnose the electronic module within the fuse block, the EMIC, the ECM, and the CAN data bus network inputs and outputs related to the various exterior lighting systems requires the use of a DRBIII(R) scan tool. Refer to the appropriate diagnostic information.

BACKUP LAMPS
The backup (or reverse) lamps have a path to ground received at all times through the vehicle wire harness from a ground point located on the frame near the left end of the tailgate sill. The backup lamps receive battery current on the backup lamp supply circuit only when the backup lamp switch circuit of the Transmission Range Sensor (TRS) integral to the gear shifter assembly is closed by the gear shifter mechanism.

BRAKE LAMPS
The brake (or stop) lamps have a path to ground at all times through the vehicle wire harness from a ground point located on the frame near the left end of the tailgate sill. The Center High Mounted Stop Lamp (CHMSL) has a path to ground at all times through the vehicle wire harness from a ground point on the left side of the dash panel. The brake lamps and CHMSL receive battery current on the brake lamp switch output circuit when the brake lamp switch is closed by the brake pedal arm.

DAYTIME RUNNING LAMPS
Vehicles manufactured for sale in Canada illuminate the low beam headlamp bulb when the engine is running and the exterior lamps are turned off. This feature is enabled by the right and left Daytime Running Lamps (DRL) relays. When the DRL relays are de-energized, they provide fused battery current from the circuit K26 relay to the headlamp low beams. When the headlamps are turned On using the left (lighting) control stalk of the multi-function switch the DRL relays are energized, which returns control of the headlamps to the headlamp switch circuitry of the multi-function switch. The circuit K26 relay is energized by the Electro-Mechanical Instrument Cluster (EMIC) whenever it receives an electronic message from the Engine Control Module (ECM) over the Controller Area Network (CAN) data bus indicating that the engine is running. The DRL and circuit relays are installed in a relay bracket located below the forward edge of the driver side front seat cushion within the driver side front seat riser.

FRONT FOG LAMPS
Vehicles equipped with optional front fog lamps have a front fog lamp relay installed in a relay bracket located below the forward edge of the driver side front seat cushion within the driver side front seat riser, a fog lamp switch installed in the cluster bezel on the instrument panel outboard of the steering column, and a fog lamp bulb installed in each of the two front lamp units. The front fog lamps have a path to ground at all times through their connection to the vehicle wire harness. The headlamp switch circuitry of the left (lighting) control stalk of the multifunction switch controls front fog lamp operation by providing battery current to the front fog lamp relay only when the low beam headlamps are selected. The fog lamp switch controls front fog lamp operation by energizing or de-energizing the front fog lamp relay control coil.

HAZARD WARNING LAMPS
With the hazard switch in the On position, the hazard switch button illuminates and the right and left turn signal indicators as well as the right and left turn signal lamps begin to flash on and off. When the hazard warning system is activated, the hazard switch circuitry within the multi-function switch and the wipers, turn signals and engine start control module electronic circuitry within the fuse block will repeatedly energize and de-energize the turn signal relay located in the fuse block. The turn signal relay switches battery current from a fused B(+) fuse in the fuse block to the turn signal indicators and the turn signal lamps. The flashing of the hazard switch button illumination lamp is also controlled by the output from the turn signal relay.

HAZARD WARNING LAMPS
The headlamp system includes the exterior lighting switches integral to the left (lighting) control stalk of the multi-function switch as well as the low and high beam bulbs installed in the right and left front lamp units (Fig. 1). The headlamp bulbs have a path to ground at all times through the vehicle wire harness. The exterior lighting switches control headlamp operation by providing battery current to the selected low or high beam bulbs. Each front lamp unit includes two integral adjustment screws to be used for static horizontal and vertical aiming of the headlamp beam reflectors.

HEADLAMP LEVELING
The headlamp leveling system includes a leveling actuator motor integral to each front lamp unit, and a rotary thumbwheel actuated headlamp leveling switch in the cluster bezel on the instrument panel outboard of the steering column. The headlamp leveling system allows the headlamp beam reflectors to be adjusted to one of four vertical positions to compensate for changes in inclination caused by the loading of the vehicle suspension. The actuator motors are mechanically connected through an integral pushrod to an adjustable headlamp reflector. The headlamp leveling switch is a resistor multiplexed unit that provides one of four voltage outputs to the headlamp leveling motors. The headlamp leveling motors will move the headlamps to the selected position based upon the voltage input received from the switch. The headlamp leveling motors and switch have a path to ground at all times. The headlamp leveling components operate on battery current received through the park lamps circuit so that the system will only operate when the exterior lighting is turned on.

PARK LAMPS

Lighting Switch:

The park lamps system includes the exterior lighting switches integral to the left (lighting) control stalk of the multi-function switch, the front park/side marker lamps, the front position lamps, the rear park lamps, the rear side marker lamps, the optional clearance lamps, and the license plate lamps. Each of these lamps are provided with a path to ground at all times through the vehicle wire harness. The exterior lighting switches control the park lamp operation by providing battery current through the park lamps circuit to the appropriate lamp bulbs.

TURN SIGNAL LAMPS
When the left (lighting) control stalk of the multifunction switch is activated, the turn signal system illuminates the selected right or left turn signal indicator and the turn signal lamps begin to flash. The turn signal lamps include a bulb integral to each front lamp unit and each tail lamp unit, as well as a repeater lamp bulb located on each front fender above the front wheels. When the turn signal system is activated, the turn signal switch circuitry within the multi-function switch and the electronic circuitry of the wipers, turn signals and engine start control module within the fuse block will repeatedly energize and de-energize the turn signal relay located in the fuse block. The turn signal relay switches battery current from a fused ignition switch output fuse in the fuse block to the appropriate turn signal indicator and turn signal lamps.

The ElectroMechanical Instrument Cluster (EMIC) contactless relay will generate repetitive, audible turn signal "click" sounds to emulate the sounds of a conventional electro-mechanical turn signal flasher at one of two rates to coincide with the flashing of the turn signals. The slow rate emulates normal turn signal operation, while the fast rate emulates "bulb out" turn signal operation.