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 manufac-

tured 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

both

front

lamp

units

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 head-
lamp 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 open-
ing. 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 inte-
gral 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 sup-
port bracket under the instrument panel and actu-
ated 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 dedi-
cated 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 vehi-
cles equipped with this option.

• Headlamp Leveling Motor - A headlamp lev-

eling 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 thumbwheel

actuated headlamp leveling switch is mounted in the
instrument cluster bezel, below the cluster and out-
board 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 inter-
face connector. Only the left (lighting), right (wiper)
control stalks and the hazard warning switch button
for the multi-function switch are visible, the remain-
der 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 light-
ing system.

• Trailer Tow Connector - Vehicles equipped

with a factory-approved, field-installed trailer towing

8L - 2

LAMPS/LIGHTING - EXTERIOR

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

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 cir-
cuits.

• 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 sig-
nals 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 multi-
function switch and feedback from the turn signal
circuits. (Refer to 8 - ELECTRICAL/POWER DISTRI-
BUTION/FUSE BLOCK - DESCRIPTION).

Hard wired circuitry connects the exterior lighting

system components to the electrical system of the
vehicle. These hard wired circuits are integral to sev-
eral 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 infor-
mation. The wiring information includes wiring dia-
grams, proper wire and connector repair procedures,
further details on wire harness routing and reten-
tion, 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 sys-
tems. The hard wired circuits and components of the
exterior lighting systems may be diagnosed and
tested using conventional diagnostic tools and proce-
dures. However, conventional diagnostic methods
may not prove conclusive in the diagnosis of the wip-
ers, 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 diagnostic 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 cir-
cuit 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 illumi-

nate 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 Run-
ning 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 ElectroMechanical Instrument Clus-
ter (EMIC) whenever it receives an electronic mes-
sage from the Engine Control Module (ECM) over the
Controller Area Network (CAN) data bus indicating
that the engine is running. The DRL and circuit K26
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

LAMPS/LIGHTING - EXTERIOR

8L - 3

seat riser, a fog lamp switch installed in the cluster
bezel on the instrument panel outboard of the steer-
ing 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 cir-
cuitry of the left (lighting) control stalk of the multi-
function 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.

HEADLAMPS

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 oper-
ation 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 lev-
eling system allows the headlamp beam reflectors to
be adjusted to one of four vertical positions to com-
pensate for changes in inclination caused by the load-
ing 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 posi-
tion 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

The park lamps system includes the exterior light-

ing switches integral to the left (lighting) control
stalk of the multi-function switch (Fig. 1), 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 har-
ness. The exterior lighting switches control the park
lamp operation by providing battery current through
the park lamps circuit to the appropriate lamp bulbs.

Fig. 1 Lighting Switch

1 - LEFT TURN SIGNAL
2 - RIGHT TURN SIGNAL
3 -EXTERIOR LIGHTING
4 - BEAM SELECT (DIMMER)
5 - OPTICAL HORN

8L - 4

LAMPS/LIGHTING - EXTERIOR

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