Hummer H2. Manual — part 354

roof lamps. The front clearance and roof lamps are grounded at G203. The rear clearance and roof lamps are
grounded at G410. If the headlamp switch is left in the ON position, the inadvertent power control feature will
turn off the park, tail, and clearance lamps, approximately 10 minutes after the ignition switch is turned to the
OFF position. If the driver places the headlamp switch in the ON position after the ignition switch has been
turned OFF, or if the ignition switch is in the ACCY position, the park, tail, and marker lamps, will remain on
until turned off or the battery runs dead.

Off-Road Lamps

The off-road lamps are available in several configurations with lights mounted on the roof and on the front
brush guard. The lamps are controlled by a single, rocker type switch, located on the overhead console. When
the switch is closed, voltage is supplied to the relays on the off-road lamps relay control circuit. When the relays
are energized, voltage is on the front, roof 1, and roof 2 off-road lamps supply voltage circuits, depending on
the configuration of lamps.

INTERIOR LIGHTING SYSTEMS DESCRIPTION AND OPERATION

Interior Lamps

The interior lighting consist of the following 2 groups. This first group includes lamps that may not be dimmed.

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The courtesy/Illuminated entry lamps

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The dome lamps

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The I/P compartment lamp

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The map lamps

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The reading lamps

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The vanity mirror lamps

Courtesy/Illuminated Entry Lamps

The courtesy/illuminated entry lamps, may be manually turned on or off by placing the interior lamp switch in
the ON or OFF position. If a door is opened, the courtesy/illuminated entry lamps illuminate. After all the doors
have been closed the courtesy/illuminated entry lamps will remain illuminated approximately 15 seconds. The
courtesy/illuminated entry lamps will also turn on prior to any door being opened, and remain illuminated
approximately 40 seconds when the driver removes the ignition key. If the interior lamp switch is turned on
when the ignition key is OFF, or the interior lamp switch is left on when the ignition key is turned OFF the
body control module (BCM) will turn off the courtesy lamps after approximately 10 minutes.

When the driver places the dome lamp defeat switch in the OFF position, the courtesy/illuminated entry lamps
will be disabled; however, the lamps will still operate from the interior lamp switch.

The left and right front door courtesy lamps are controlled, and receive voltage and ground from the drivers
door module (DDM) and the passenger door module (PDM), respectively. The BCM, DDM, and the PDM
communicate through class II serial data for the lamp illumination commands and the door ajar switches.

The remaining courtesy lamps are controlled and receive voltage from the BCM. Ground is provided to the

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

footwell lamps and all courtesy/reading lamps at G203. Ground is provided to the right middle and right rear
door at G306. Ground is provided to the left middle and left rear door at G302.

Keyless Entry Interior Illumination

When the driver uses the door key in order to unlock the doors, the body control module (BCM) receives a door
unlock signal. The BCM must have inputs that indicate that the ignition switch is OFF, the courtesy lamp
switch is OFF, and all the doors are closed. The BCM will then activate the interior lamps. The courtesy lamps
will remain on, approximately 15 seconds after the door is closed. The BCM will then turn them off through the
theater dimming feature. If the door locks are activated to the LOCK position, or if the ignition switch is turned
to either the RUN or CRANK position the courtesy lamps will turn off immediately.

When the driver uses the remote function actuator transmitter to unlock the doors, the trunk, or presses the panic
button, the BCM will keep the courtesy lamps on approximately 40 seconds. When the driver uses the remote
function actuator transmitter to lock the doors, the BCM will keep the courtesy lamps on approximately 2
seconds. If the ignition switch is turned to either the RUN or CRANK position, the courtesy lamps will turn off
immediately. The BCM will also keep the courtesy lamps on approximately 40 seconds, after an alarm event is
completed.

Vanity Lamps

The inadvertent power supply voltage circuit of the body control module (BCM) provides battery positive
voltage to each vanity mirror lamp. When the vanity mirror cover on the sunshade is opened, a switch closes to
provide a ground circuit and the vanity lamp illuminates. In the event that any of these lamps were to remain
illuminated for a period of more than 10 minutes with the ignition switch in the OFF position, the BCM will
deactivate the inadvertent power supply voltage circuit to prevent a total battery discharge condition. Ground is
provided to the vanity lamps at G203.

I/P Compartment Lamp

The inadvertent power supply voltage circuit of the body control module (BCM) provides battery positive
voltage to the instrument panel (I/P) compartment lamp. When the I/P compartment is opened, a switch closes
to provide a ground circuit and the I/P compartment lamp illuminates. In the event that any of these lamps were
to remain illuminated for a period of more than 10 minutes with the ignition switch in the OFF position, the
BCM will deactivate the inadvertent power supply voltage circuit to prevent a total battery discharge condition.
Ground is provided to the I/P compartment lamp at G203.

Reading Lamps

The inadvertent power supply voltage circuit of the body control module (BCM) provides battery positive
voltage to the reading lamps. The reading lamps and switch are integral to the courtesy/reading lamp assembly.
When the switch is closed, voltage is supplied and the lamp illuminates. In the event that any of these lamps
were to remain illuminated for a period of more than 10 minutes with the ignition switch in the OFF position,
the BCM will deactivate the inadvertent power supply voltage circuit to prevent a total battery discharge
condition. Ground is provided to the reading lamps at G203.

Battery Rundown Protection/Inadvertent Power

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

The body control module (BCM) inadvertent power supply voltage circuit provides battery positive voltage to
all of the interior reading lamps, instrument panel (I/P) compartment lamp, and both visor vanity mirror lamps.
In the event that any of these lamps were to remain illuminated for a period of more than 10 minutes with the
ignition switch in the OFF position, the BCM will deactivate the inadvertent power supply voltage circuit to
prevent a total battery discharge condition.

The BCM also utilizes the inadvertent power supply voltage circuit as a lamp request signal circuit when none
of the lamps in the circuit are illuminated. When a lamp switch is activated, the BCM receives the request for
lamp illumination and switches to supplying voltage to the inadvertent power supply voltage circuit.

Interior Lamps Dimming

The second group includes lamps which may be dimmed. This group may use a combination of vacuum
fluorescent (VF) illumination and incandescent lamps.

When the ignition switch is turned to the RUN position, the radio's VF displays turn on at maximum brightness.
When the park lamps are on, all incandescent back lighting turns on at the dimming level indicated by the
instrument panel (I/P) dimmer switch. At the same time all VF displays dim to match the indicated dimming
level. The panel dimmer switch potentiometer is an input to the body control module (BCM). When the driver
selects a dimming setting by moving the I/P dimming switch potentiometer, all incandescent back lighting
lamps are provided with a specific voltage. When the I/P dimmer switch is moved from MIN to MAX, all VF
displays, as well as all incandescent back lighting, respond from minimum intensity to maximum brightness in
response to the I/P dimmer switch. The following switches and components have back lighting when the park
lamps are on.

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The instrument panel cluster (IPC)

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The radio

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The window and heated seat switches

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The garage door opener switch

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The sunroof switch

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The HVAC control assemblies

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The headlamp and panel dimmer switch

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The tow/haul switch

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The transfer case shift control switch

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The height control switch

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The PSIR disable switch

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The PRNDL lamps

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The traction control switch

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The steering wheel control switches

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The rear wiper/washer switch

The left and right front door switch illumination is controlled, receives voltage and ground from the drivers
door module (DDM) and the passenger door module (PDM), respectively. The radio is also a class II module

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2

and has full control of its illumination. The BCM, DDM, PDM, and radio communicate through class II serial
data for the lamp illumination commands.

The I/P cluster illumination lamps receive voltage and are controlled by the BCM on the instrument panel lamps
dimming supply voltage circuit. Ground for the instrument panel lamps is at G203.

The various switches, HVAC control assembly, and the PRNDL lamps receive voltage, and are controlled by
the BCM on the instrument panel lamps dimming control circuit. Ground for the rear window switches is at
G302 and G306. Ground for the traction control switch, steering wheel controls, and the rear window/wiper
switch is at G200. Ground for the remaining switches is at G203.

The following indicators receive voltage from the BCM and are controlled by various modules.

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The traction control switch traction control OFF indicator

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The height control switch high clearance indicator

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The transfer case control switch 4WD position indicator

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The heated seat indicators

The indicators receive voltage from the BCM on the LED dimming circuit. Ground/control for the indicators is
from the various modules. The modules controlling the above indicators are as follows:

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The electronic brake control module (EBCM)

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The air suspension module

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The driver door module (DDM)

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The passenger door module (BCM)

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

Special Tools

Illustration

Tool Number/Description

J 25300-D

Headlamp Aimer

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Lighting Systems - Hummer H2