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Chevrolet Silverado / GMC Sierra. Manual - part 1550
The body control module (BCM)
The driver information center (DIC)
The rear door lock/unlock relay (LBEC)
The door lock actuators in each of the doors
Door Lock System Controls
The power door lock system can be controlled by any of the following:
A power door lock or unlock switch activation
A keyless entry transmission
An automatic door lock function
A delay lock function
Door lock cylinder switch activation
Lockout Prevention
Power Door Lock System Operation
The front power door lock switches are integral components of the driver door module (DDS)
and passenger door module (PDS). The switches are 2 position normally open rocker switches.
When placed in either the lock or unlock positions, the switches provide a direct input to the
DDS or PDS. The DDS or PDS monitors these inputs and sends a GMLAN message indicating a
change in the switch's respective position. Modules which activate the power door lock actuators
receive the lock or unlock message and activate the actuator in the appropriate direction to lock
or unlock the vehicle's doors.
The modules which activate the power lock motors are:
The DDS (driver door lock actuator)
The PDS (passenger front door lock actuator)
The BCM (both rear door lock actuators)
The DDS and PDS are directly connected to the respective door lock actuator through the lock
and unlock control circuits. Once a door lock or unlock request has been received, the module
will supply battery voltage to one side of the actuator and ground the other causing the doors to
lock or unlock.
The rear passenger doors are controlled by the BCM through the rear door lock/unlock relay
which is incorporated onto the printed circuit board in the LH BEC. The BCM controls the
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
unlock relay by providing ground to energize the coil and controls the lock relay by providing
battery voltage to energize the relay coil. The energized the relay and allows voltage to be
applied to either the door lock motor lock or unlock circuits. Since the other side of the door
lock actuator is connected to the normally closed contacts of the opposing relay to ground, the
doors lock or unlock.
Programmable Automatic Door Locks
The automatic door lock feature can be programmed to control the door lock system. The
automatic door lock feature is factory programmed to have all doors lock and unlock.
When the automatic door lock feature is programmed to control the door lock system, the driver
door switch (DDS), passenger door switch (PDS) and body control module (BCM) will lock the
vehicle doors if the following inputs are true:
Ignition 1 input is active.
All door ajar switch inputs are inactive.
Transmission is shifted out of PARK.
This automatic door lock function will only occur once per ignition cycle unless, a door ajar
switch input changes state to active and back to inactive. Then the DDS, PDS and BCM will lock
all doors again.
Once the automatic door lock feature has locked the doors, the BCM will then unlock all the
doors when the transmission is shifted into PARK.
Lockout Prevention
This feature prevents the locking of the driver door if the ignition key is left in the ignition lock
cylinder. If a lock function occurs from any door lock switch and the body control module
(BCM) senses an active state on either the left front door latch signal, secondary door latch
switch signal and the key in ignition switch signal circuit is in the YES state, the BCM, driver
door switch (DDS) and passenger door switch (PDS) will lock the doors and then the DDS will
unlock the driver door.
Delayed Locking Operation
With any door open and a door lock switch is activated in the lock position, the driver door
switch (DDS), passenger door switch (PDS) and the body control module (BCM) will go into a
lock pending state. The BCM will also give 3 audible chimes. When the door is closed, the DDS,
PDS and the BCM will lock the doors after approximately 5 seconds. This feature can be
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
overridden by activating the door lock switch a second time and the doors will lock even with a
door open.
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Vehicle Access - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
2008 DRIVELINE/AXLE
Propeller Shaft - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
SPECIFICATIONS
FASTENER TIGHTENING SPECIFICATIONS
SEALERS, ADHESIVES, AND LUBRICANTS
COMPONENT LOCATOR
DRIVELINE DISASSEMBLED VIEWS
Application
Specification
Metric
English
Center Bearing Mounting Bolt
40 N.m
30 lb ft
Yoke Retainer Bolts
25 N.m
18 lb ft
Application
Type of Material
GM Part Number
Propeller Shaft Splines (Front Propeller
Shaft and One-Piece RWD Propeller Shaft
w/ Automatic Transmission)
Lubricant
12345879 or equivalent
meeting GM Specification
9985830
2008 Chevrolet Silverado 1500
2008 DRIVELINE/AXLE Propeller Shaft - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
2008 Chevrolet Silverado 1500
2008 DRIVELINE/AXLE Propeller Shaft - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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