The interior lighting system for this model includes incandescent lighting on two separate circuits: the dome/courtesy
lamp circuit and the panel lamps dimmer circuit. The lamps on the dome/courtesy circuit include:

•

Cargo Lamps (4) - The standard equipment cargo lamps are integral to the Center High Mounted Stop Lamp
(CHMSL) located on the roof rear header above the rear glass on the back of the cab. One cargo lamp bulb
is behind a clear lens on each outboard side of the center red lens of the CHMSL. The cargo lamps are
manually activated or deactivated by depressing the momentary cargo lamps push button of the headlamp
switch on the instrument panel to illuminate the cargo area of the pick-up box.

•

Glove Box Lamp (1) - A glove box lamp with an integral switch is standard equipment on quad cab models.
The lamp and switch are located at the upper right corner of the instrument panel glove box opening and
illuminates whenever the glove box is opened.

•

Front Dome/Reading Lamps (2) - The standard front dome/reading lamp includes two bulbs and two integral
push button actuated switches. This lamp is located in the center of the headliner near the windshield header.
In vehicles with an optional overhead console these lamps are replaced by two dome/reading lamps that are
integral to the overhead console. The overhead console lamps have switches that are actuated by depressing
the lamp lenses.

•

Rear Dome/Reading Lamps (4) - A standard rear dome lamp is located in the headliner at the back of the
cab above the rear window. On club cab models this lamp is activated by the door ajar switches or the interior
lighting thumbwheel on the headlamp switch. On quad cab models the standard rear dome lamp is replaced
with a rear dome/reading lamp that includes a switch that is actuated by depressing the lamp lens.

Most controls on the instrument panel and other controls located elsewhere on the interior of the vehicle are illu-
minated for night visibility. Some have miniature incandescent bulbs or Light-Emitting Diode (LED) units that are

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LAMPS/LIGHTING - INTERIOR - SERVICE INFORMATION

soldered to internal circuit boards and are not serviceable. The replaceable incandescent bulbs or bulb/bulb holder
units in this vehicle include:

•

Center Bezel Lamp - An optional center bezel lamp with a replaceable bulb is located on the underside of the
instrument panel center bezel below the heater/air conditioner control to illuminate an optional center console
forward storage bin and cup holders.

•

Compass Mini-Trip Control Illumination Lamps - The optional Compass Mini-Trip Computer (CMTC) has
three replaceable bulb/bulb holder units to illuminate its controls.

•

Front Heater-Air Conditioner Control Illumination Lamps - The heater-air conditioner control panel has two
replaceable bulb/bulb holder units to illuminate its controls.

Other components of the interior lighting system for this model include:

•

Door Ajar Switches - A door ajar switch is integral to the door latch mechanism of each front and rear door.

•

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 vertical thumbwheel for selecting the panel lamps
dimming level and for interior lighting control. A Parade position of the thumbwheel illuminates all Vacuum Flu-
orescent 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. (Refer to 8 - ELECTRICAL/LAMPS/LIGHTING - EXTERI-
OR/HEADLAMP SWITCH - DESCRIPTION).

•

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. (Refer to 8 - ELECTRICAL/INSTRUMENT CLUSTER - DESCRIPTION).

Hard wired circuitry connects the interior 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
interior 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.

OPERATION

The interior lighting systems can be divided into two general classifications based upon the circuit that controls their
operation: The courtesy lamp circuit, or the panel lamps dimmer circuit. The hard wired circuits and components of
the interior lighting systems may be diagnosed and tested using conventional diagnostic tools and procedures. Refer
to the appropriate wiring information. However, conventional diagnostic methods may not prove conclusive in the
diagnosis of the ElectroMechanical Instrument Cluster (EMIC), or the Controller Area Network (CAN) data bus. The
most reliable, efficient, and accurate means to diagnose the EMIC, the CAN data bus, or the electronic bus mes-
sage inputs and outputs related to the various interior lighting systems requires the use of a diagnostic scan tool.
Refer to the appropriate diagnostic information.

COURTESY LAMP CIRCUIT

Depending upon the selected vehicle options the courtesy lamp circuit may include the dome and dome/reading
lamps located in the headliner near the windshield and above rear window at the back of the cab, the cargo lamps
located near the center of the rear roof header, and the glove box lamp in the top of the glove box opening in the
instrument panel. The lamps in the courtesy lamp circuit are provided with a path to ground at all times. The EMIC
controls the output of battery voltage for the courtesy lamps in this circuit based upon hard wired inputs from the
door ajar switches, the headlamp switch and the ignition switch.

After all of the ajar switch inputs to the EMIC transition to open, the EMIC will keep the courtesy lamps illuminated
for about 30 seconds, then fade the lamps to off (theater dimming) over about three seconds. The EMIC also pro-
vides courtesy lamp operation based upon a resistor multiplexed input from the vertical thumbwheel on the head-
lamp switch, and provides an illuminated entry feature in response to certain electronic message inputs received
from the Sentry Key REmote Entry Module (SKREEM) and the Occupant Restraint Controller (ORC) over the CAN
data bus. A resistor multiplexed courtesy lamp defeat input from the vertical thumbwheel of the headlamp switch will
cause the EMIC to override normal courtesy lamp operation based upon inputs from all of the ajar switches.

LAMPS/LIGHTING - INTERIOR - SERVICE INFORMATION

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