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Chevrolet Silverado / GMC Sierra. Manual - part 3001
The driver master control switches are integrated into the DDS. When a power window switch is
activated in the up or down positions the DDS supplies power and ground to the window motor
control circuits to drive the window motor in the required direction. Prior to activating a power
window motor the DDS will supply the control circuit with a low current bias voltage in order to
determine that a short to ground condition does not exist and during window motor operation the
DDS continues to monitor the motor current to verify proper window motor operation.
The DDS controls the passenger window through a GMLAN message to the PDS. When a power
window switch is activated in the up or down positions the PDS supplies power and ground to
the window motor control circuits to drive the window motor in the required direction. Prior to
activating a power window motor the PDS will supply the control circuit with a low current bias
voltage in order to determine that a short to ground condition does not exist, and during window
motor operation the PDS continues to monitor the motor current to verify proper window motor
operation. (Scan tool support is available for this system)
Driver Power Window Operation (RPO A31/AN3/DL3)
The switch for the driver power window has 3 positions Up, Down and Express Down and it's
position is a direct input into the DDS. Upon receiving a request for power window operation
(switch activation), the DDS supplies voltage to the power window motor up or down circuit and
grounds the down or up circuit and the power window motor moves the window UP or DOWN
direction.
Front Passenger Power Window Operation (RPO A31/AN3/DL3)
The switch for the front passenger power window has 2 positions UP and DOWN, and it's
position is a direct input into the PDS. Upon receiving a request for power window operation
(switch activation), the PDS supplies voltage to the power window motor right front up or down
circuit and grounds the opposite and the power window motor runs to drive the window UP or
DOWN.
The front passenger power window can also be operated from the driver master control. The front
passenger window switch on the driver master control has 2 positions UP and DOWN and it's
position is a direct input into the DDS. Upon receiving a request for front passenger power
window operation, the DDS transmits a GMLAN message indicating the changed switch position.
When the PDS receives this message, the PDS supplies voltage to the power window motor right
front up or down circuit and grounds the opposite and the power window motor runs to move the
window UP or DOWN.
Rear Passenger Power Window Operation (RPO A31/AN3/DL3)
The body control module (BCM) monitors the window UP/DOWN command from the DDS.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Fixed and Moveable Windows - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
When the rear window UP or DOWN command is received, the BCM sends a signal to the
appropriate rear window switch. The rear window switches continuously monitor the up and
down signal circuits, if no function is being commanded, the signal voltage is at approximately
B+ voltage. If the UP or DOWN function is commanded, the BCM signal voltage drops
approximately 5 volts and the appropriate rear window switch will then command the window in
the UP or DOWN direction.
Rear Power Window Lockout Operation (RPO A31/AN3/DL3)
The BCM monitors the window lockout command from the DDS. When the rear window switch
operation is authorized, the BCM sends a signal to the rear window switches allowing for normal
window operation from the rear switches. If the rear window lockout function is commanded, the
BCM signal voltage drops approximately 5 volts which disables the rear window switches and
the rear windows will only operate when the BCM receives a command from the driver master
control. The lockout feature will remain in effect until the ignition switch is cycled or the driver
enables the rear windows by pressing the rear window lockout switch again.
Power Window System Controls (RPO A31 W/O AN3, DL3)
The power window system will operate anytime the RAP system is active or when the ignition
switch is in the ACCY or ON position.
The driver and passenger door lock and side window switches are integrated control assemblies.
The driver and front passenger window switches are normally open, 3 position rocker type
switches, with detents for Up, Down, and Express Down. The driver window master control rear
passenger window switches are normally open, 2 position rocker type switches, with detents for
Up and Down. The driver window master control rear window lockout switch is a push button
type switch that provides an active signal to the driver window switch whenever pressed.
Whenever the rear window lockout switch is pressed the driver window switch will enable or
disable the function of the rear window switches depending on the current state, and illuminate
the switch indicator whenever the function is active. (No scan tool support for this system)
Driver Power Window Operation (RPO A31 W/O AN3, DL3)
The switch for the driver power window has 3 positions UP, Down and Express Down and it's
position is a direct input into the driver window switch. Upon receiving a request for power
window operation (switch activation), the driver window switch supplies voltage to the power
window motor left front up or down circuit and grounds the opposite and the power window
motor runs to move the window up or down.
Front Passenger Power Window Operation (RPO A31 W/O AN3, DL3)
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Fixed and Moveable Windows - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
The switch for the front passenger power window has 3 positions UP, Down and Express Down
and it's position is a direct input into the passenger window switch. Upon receiving a request for
power window operation (switch activation), the passenger window switch supplies voltage to
the power window motor right front up or down circuit and grounds the opposite and the power
window motor runs to drive the window up or down.
The front passenger power window can also be operated from the driver window switch. The
right front window switch on the driver master control has 3 positions Up, Down and Express
Down and its position is a direct input into the driver window switch. Upon receiving a request
for front passenger power window operation, the driver window switch transmits a command
signal indicating the changed switch position. When the passenger window switch receives this
message, the passenger window switch supplies voltage to the power window motor right front up
or down circuit and grounds the opposite and the power window motor runs to move the window
up or down.
Rear Passenger Power Window Operation (RPO A31 W/O AN3, DL3)
The rear passenger power windows can also be operated from the driver window switch. The left
rear and right rear window switches on the driver master control has 2 positions, Up and Down,
and its position is a direct input into the driver window switch. Upon receiving a request for rear
passenger power window operation, the driver window switch transmits a command signal to the
appropriate rear window switch which receives this message, the rear window switch then
supplies voltage to the power window motor up or down circuit and grounds the down or up
circuit and the power window motor runs to move the window up or down.
Rear Power Window Lockout Operation (RPO A31 W/O AN3, DL3)
The rear window lockout function is operated from the driver master control through a command
signal to the rear door power window switches. When the rear door power window switches
receives an active lockout command, the rear door power window switches are disabled and the
indicator lamp on the lockout switch will illuminate. Once disabled, the lockout feature will
remain in effect until the ignition switch is cycled or the driver enables the rear windows by
pressing the rear window lockout switch again.
Power Sliding Rear Window
NOTE: Power window lockout switch disables left rear and right rear passenger window
switches only and has no effect on the operation of the power sliding window switch.
The power sliding rear window motor is controlled from the rear window OPEN/CLOSE switch
through OPEN and CLOSE relays. The OPEN/CLOSE switch is supplied voltage from the body
control module (BCM) accessory voltage output circuit. When the switch is pressed in the OPEN
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Fixed and Moveable Windows - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
or CLOSED position the OPEN or CLOSED relay coil will be supplied accessory voltage and
energized through the appropriate relay control circuit. While the OPEN and CLOSE relays are
in a de-energized state both motor control circuits will be closed to ground. When one of the
relays is energized its motor control circuit will be closed to the battery voltage supply circuit
and the other motor control circuit will remain grounded through the de-energized relay.
REAR WINDOW DEFOGGER DESCRIPTION AND OPERATION
Rear Window Defogger System Components
The rear window defogger system consist of the following components:
HVAC control module
REAR DEFOG relay
Rear window defogger grid
Rear Window Defogger Operation
When the rear defogger switch is pressed, the HVAC control module will illuminate the rear
window defogger indicator and will supply voltage to the defog relay coil. Battery positive
voltage is supplied at all times to the defog relay switched input and the defog relay coil is always
grounded. This allows battery positive voltage from the relay switch contacts to the rear window
defogger grid. The HVAC module also sends a request to the driver door module and passenger
door module to activate the heated mirrors, if equipped.
When the rear window defogger is initially activated, the defogger cycle will last 10 minutes,
further requests will result in 5 minute defogger cycles.
SPECIAL TOOLS AND EQUIPMENT
SPECIAL TOOLS
Illustration
Tool Number/ Description
J-9886-01
Door Handle Clip Remover
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Fixed and Moveable Windows - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
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