Lighting 2-43
Interior Lighting Systems
Description and Operation
Interior Lamps
The interior lighting system consist of two groups. This
first group includes lamps that are not be dimmed.
• Dome/reading lamps
• Instrument panel compartment lamp
• Instrument panel courtesy lamps
• Overhead console accent lamp
• Sunshade mirror lamps
Dome Lamps
The dome lamps are controlled by door ajar inputs to
the K9 Body Control Module (BCM). When any door is
opened, the door ajar switch contacts close and the
BCM receives a door-open input. The BCM responds
by sending a serial data messag e to the A103 Roof
Console. The Roof Console responds by applying
battery voltage to the dome lamps illuminating the
dome lamps. The BCM will also send a serial data
message to request the dome lamps on when a door
lock/unlock request is activated with the key fob. After
all doors have been closed, the dome lamp will remain
illuminated approximatel y 3 seconds after the last door
closes. In the event that the dome lamp were to remain
illuminated for more than 10 minutes with the ignition
switch in the OFF position, the BCM will deactivate the
dome lamp control circuit to prevent total battery
discharge. The dome lamps will turn OFF using the
theater dimming feature when controlled by the BCM.
Center Console Compartment Lamp
The K9 Body Control Module (BCM) supplies battery
voltage to the center console lamp. When the center
console lid is opened, the switch contacts close
allowing battery voltage to flow illuminat ing the center
console lamp. In the event that the center console lamp
were to remain illuminated for more than 10 minutes
with the ignition/v ehicle off, the BCM will deactiva te the
courtesy lamp control circuit to prevent total battery
discharge.
Keyless Entry Interior Illumination
When the operator uses the keyless entry transmitter in
order to unlock the doors, the K9 Body Control Module
(BCM) receives a door-unlock signal. The BCM must
receive inputs from various systems that indicate that
the ignition switch is OFF, the courtesy lamp switch is
OFF, and all doors are closed before the BCM will
activate the interior lamps. After all doors have been
closed, the courtesy lamps will turn OFF immediately if
the ignition switch is turned to the ON position, the door
locks are LOCKED, or approximately 20 seconds after
the last door closes. The BCM will turn off the courtesy
lamps through the theater dimming feature. The BCM
keeps the courtesy lamps on for 40 seconds after an
alarm event is completed.
Reading Lamps
When a reading lamp button is pressed, the switch
contacts close providing a path to ground for the signal
circuit from the A103 Roof Console. The roof console
responds by applying battery voltage to the appropriate
reading lamp control circuit illuminatin g the reading
lamp. If the operator inadvertently leaves a reading
lamp ON, the BCM will send a serial data message to
turn all interior lighting off after 10 minutes has passed
to prevent total battery discharge.
Sunshade Mirror Lamp
The inadvertent power supply voltage circuit from the
K9 Body Control Module (BCM) provides battery
voltage to the passenger side sunshade mirror lamp.
When the sunshade mirror cover is opened, a switch
closes providing ground and the sunshade lamp
illuminates. If the operator inadvertently leaves the
sunshade mirror cover open with the lamp ON, the
BCM will turn all interior lamps OFF after 10 minutes
has passed to prevent total battery discharge.
Interior Lamps Dimming
The second group includes lamps which may be
dimmed. This group may use a combination of light
emitting diodes (LED), incandescent lamps, and pulse
width modulation (PWM) voltage illumination.
• Audio/Video Input Adapter
• Door lock switch – driver
• Door lock switch – passenger
• Hazard switch
• HVAC control head assembly
• Ignition mode switch
• Instrument panel dimmer switch
• Multifunction switch – center console
• Multifunction switch – instrument panel
• Outside rearview mirror switch
• Park brake switch
• Radio
• Seat memory switch – driver
• Seat memory switch – passenge r
• Steering wheel controls switch – left
• Steering wheel controls switch – radio presets
• Steering wheel controls switch – radio volume
• Window switch – driver
• Window switch – passenger
With the S30 Headlamp Switch in the PARK or HEAD
position, the park lamp switch signal circuit provides an
input to the K9 Body Control Module (BCM). The BCM
responds by applying voltage to the backlight dimming
control circuits illuminating all compone nts with interior
backlighting. All interior backlighting turns on at the
dimming level set by the dimmer buttons within the
headlamp switch. The headlamp switch is used to
increase and decrease the brightness of the interior
backlighting components. The BCM provides a signal
circuit and a low reference circuit to the headlamp
switch for backlight dimming. When a dimming button is
pressed, the signal circuit becomes grounded through
the appropriate resistor internal to the headlight switch
and voltage from the BCM will decrease accordingly.
The BCM interprets the signal and responds in two
ways. The BCM applies a pulse width modulated
(PWM) voltage through the LED dimming control
circuits illuminating the interior backlighting to the
requested level of brightness. The BCM also sends a
2022 - Silverado 1500 (New) Electrical Body Builder Manual
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