Lamps/Lighting - Exterior

The exterior lighting system for this model includes the following exterior lamp units:
- Cab Clearance Lamps (1) - Vehicles equipped with this option have five individual amber clearance lamp units mounted across the roof panel just rearward of the upper windshield header.
- Center High Mounted Stop Lamp (6) - A standard equipment Center High Mounted Stop Lamp (CHMSL) is centered on the cab roof header panel just above the back glass opening at the rear of the cab. This CHMSL also incorporates two integral cargo lamps, one located at each outboard side of the CHMSL.
- Front Fog Lamps (5) - Vehicles equipped with this option have a fog lamp unit mounted near each outboard end of the front bumper support, behind the lower portion of the front fascia.
- Front Lamp Units (3) - A standard equipment front lamp unit is mounted to the front of each front fender panel on either side of the grille opening.
- License Plate Lamp (9) - A standard equipment rear license plate lamp unit is mounted to each outboard vertical surface of the license plate tub formation in the center of the rear bumper on pickup models. On cab and chassis models the license plate lamp function is integral to the left rear lamp unit.
- Rear Fender Marker Lamps (4) - Vehicles equipped with dual rear wheels have four individual rear fender marker lamp units mounted to the rear fenders. An amber lamp is located forward of each rear wheel opening and a red lamp is located rearward of each rear wheel opening.
- Rear Lamp Units (8) - A standard equipment rear lamp unit is mounted to the rear of each quarter panel on either side of the tailgate opening of pickup models. On cab and chassis models a rear lamp unit is mounted on the outboard side of each frame rail near the rear of the vehicle.
- Tailgate Marker Lamp (7) - Vehicles equipped with dual rear wheels have a single red tailgate marker lamp unit mounted to the center of the outer tailgate panel below the tailgate latch release handle.
- Underhood Lamp (2) - Vehicles equipped with this option have a single underhood lamp unit with an integral automatic mechanical (non-mercury) switch. The lamp and switch unit is mounted to the underside of the inner hood reinforcement above the right side of the engine compartment.

These exterior lighting lamp units and their controls are combined to provide the following exterior lighting features:
- Backup Lamps - The backup (or reverse) lamps include a bulb, reflector and lens that are integral to each rear lamp unit.
- Brake Lamps - The brake (or stop) lamps include a bulb, reflector and lens that are integral to each rear lamp unit, and the CHMSL bulb and lens.
- Daytime Running Lamps - Vehicles manufactured for sale in Canada illuminate the high beam filament of the headlamp bulb in each front lamp unit to serve as the Daytime Running Lamps (DRL).
- Exterior Lamp Fail-Safe Operation - The EMIC provides a fail-safe feature which will automatically turn on the low beam headlamps and all park lamps when the ignition switch is in the On position and there is no detected input from the headlamp switch.
- Exterior Lamp Load Shedding - The Totally Integrated Power Module (TIPM) provides a battery saver feature which will automatically turn off all exterior lamps that remain on with the ignition switch in the Off position after a timed interval of about eight minutes.
- Front Fog Lamps - The optional front fog lamps include the bulb, reflector and lens of each adjustable front fog lamp unit.
- Hazard Warning Lamps - The hazard warning lamps include the right and left turn signal bulbs, reflectors and lenses of each front and rear lamp unit.
- Headlamp Delay - On vehicles equipped with this optional feature, the low or high beam headlamps remain illuminated for a dealer-programmable delay period of 30, 60 or 90 seconds when the headlamp switch is turned to the Off position after the ignition switch has been turned to the Off position.
- Headlamps - The headlamps include a single, dual filament halogen bulb, an adjustable reflector and a clear lens integral to each front lamp unit.
- Optical Horn - Also known as flash-to-pass, the beam selection function of the multi-function switch control stalk has a momentary intermediate position that allows the headlamp high beams to be flashed momentarily, without changing the headlamp beam selection.
- Park Lamps - The park lamps include the park and side marker bulbs, reflectors and lenses integral to each front and rear lamp unit as well as the bulbs and lenses of the rear license plate lamps. The cab clearance lamps, the dual rear wheel rear fender marker lamps and tailgate marker lamp are also included In the park lamps circuit of vehicles equipped with these optional exterior lamps.
- Turn Signal Lamps - The turn signal lamps include the turn signal bulbs, reflectors and lenses that are integral to the right and left front and rear lamp units. Other components of the exterior lighting system for this model include:
- Backup Lamp Switch - A plunger-type backup lamp switch is installed through the transmission housing of vehicles equipped with a manual transmission and is actuated by the shifter mechanism within the transmission when Reverse gear is selected. Depending upon the transmission model, either a stand-alone Transmission Range Sensor (TRS), or a TRS that is integral to the solenoid pack on the valve body performs the backup lamp switch function on vehicles with an automatic transmission.
- Brake Lamp Switch - A plunger-type brake lamp switch is located on the steering column support bracket under the instrument panel and is actuated by the brake pedal arm.
- Headlamp Switch - A headlamp switch is located on the left side of the instrument panel, below and outboard of the steering column. The headlamp switch includes a rotary knob that is rotated to turn the park lamps and headlamps On or Off, and a push button switch for selecting the cargo lamps. The rotary knob is pushed inward for selecting the optional front fog lamps on vehicles so equipped. The headlamp switch also 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, and for interior lighting control.
- Instrument Cluster - The ElectroMechanical Instrument Cluster (EMIC) is also known as the Cab Control Node (CCN) in this vehicle. The EMIC/CCN is located in the instrument panel above the steering column opening, directly in front of the driver.
- Multi-Function Switch - The multi-function switch is 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 push button that extends from the top of the switch is used to select the hazard warning lamps.
- Park Brake Switch - A park brake switch is located on the park brake lever mechanism on the cowl side inner panel below the instrument panel, to the left of the steering column.
- Totally Integrated Power Module - The Totally Integrated Power Module (TIPM) is located in the engine compartment, near the battery.
- Trailer Tow Wiring - Standard equipment in all vehicles is a 4-way trailer tow wire harness take out and a 4-pin light duty trailer tow connector that is located behind the rear bumper. An optional factory-installed trailer tow package supplements the 4-way harness and connector with a 7-way trailer tow wire harness and a sealed, heavy duty 7-pin trailer tow connector installed in the left side of the forward vertical surface of the license plate tub formation in the center of the rear bumper. This optional trailer tow package also includes a 4-way electric trailer brake wiring provision and connector located on top of the large body harness connection under the instrument panel to the left of the brake pedal, as well as an electric trailer brake pigtail harness and an instruction card that are stored in the glove box when the vehicle is shipped from the factory.

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 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 methods. Refer to the appropriate wiring information.

However, conventional diagnostic methods may not prove conclusive in the diagnosis of the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Control Node/CCN), the Totally Integrated Power Module (TIPM), the Powertrain Control Module (PCM) or the Controller Area Network (CAN) data bus. The most reliable, efficient, and accurate means to diagnose the EMIC, the TIPM, the PCM, the CAN data bus or the electronic bus message inputs and outputs related to the various exterior lighting systems requires the use of a diagnostic scan tool.