Power Door Locks System Components
The power door locks system consists of the following components:
• | Body Control Module (BCM) |
• | Vehicle Interface Unit (VIU) |
• | Driver door lock switch |
• | Front passenger door lock switch |
• | Driver lock cylinder switch |
• | Front passenger lock cylinder switch |
• | Door lock actuators in each of the doors |
Door Lock System Controls
The power door lock system is controlled by the BCM and can be activated
by any one of the following:
• | A door lock switch Lock or Unlock actuation |
• | A door lock cylinder switch Unlock actuation |
• | A keyless entry transmitter actuation |
• | An OnStar Unlock actuation using the vehicle interface unit (VIU) |
Door Lock Operation
When the BCM detects a transition of either of the door lock switches
to the Lock position, it switches the door lock actuator lock control circuit
to voltage. Since the lock actuator unlock control circuits are at ground
potential within the BCM, all the door lock actuators transition to the Lock
position.
Driver Door Unlock Operation
When the BCM detects a transition of either of the door lock switches
to the Unlock position, it switches the driver door lock actuator unlock control
circuit to voltage. Since the door lock actuator lock control circuit is at
ground potential within the BCM, the driver door lock actuator transitions
to the Unlock position.
The driver door lock actuator unlock control circuit is a dedicated
control circuit used only for the driver door lock actuator. This is done
so that the driver door may be unlocked individually before unlocking the
passenger doors using a keyless entry transmitter or an automatic door unlock
function, if programmed.
Passenger Door Unlock Operation
When the BCM detects a transition of either of the door lock switches
to the Unlock position, it switches the door lock actuator unlock control
circuits to voltage. Since the door lock actuator lock control circuit is
at ground potential within the BCM, the passenger door lock actuators transition
to the Unlock position.
The door lock actuator unlock control circuits are dedicated control
circuits used only for the passenger door lock actuators. This is done so
that the driver door may be unlocked individually before unlocking the passenger
doors using a keyless entry transmitter or an automatic door unlock function,
if programmed. When this feature is active, the BCM will require a repeated
unlock command to unlock the passenger doors. However, all doors
will unlock when the unlock input is from a door lock switch.
Automatic Door Lock/Unlock
The automatic door lock/unlock function is a Vehicle Personalization
feature with the following four programmable modes of operation:
- The automatic door lock feature is disabled.
- All of the doors lock when the vehicle is shifted out of Park
with the ignition ON.
- All of the doors lock when the vehicle is shifted out of Park
with the ignition ON, and all of the doors unlock when the ignition is turned
OFF.
- All of the doors lock when the vehicle is shifted out of Park
with the ignition ON, and all of the doors unlock when the vehicle is shifted
into Park.
The automatic door lock function can only be enabled by the BCM if the
driver door switch is in the Inactive state, meaning the door is closed. For
information on programming the automatic door locks, refer to
Vehicle Personalization
in Personalization.
Lockout Prevention
This function is intended to prevent the vehicle operator from locking
the doors if the key is left in the ignition and the driver door is open.
The lockout prevention function can be overridden by the BCM if the BCM receives
a door Lock input for longer than 3 seconds.
Last Door Closed Locking (LDCL)
The LDCL function is a Vehicle Personalization feature that is intended
to allow the doors to be locked while passengers are exiting the vehicle.
When LDCL is in Active Mode, the BCM will delay locking of the vehicle doors
for 5 seconds after all of the doors have been closed. The LDCL function will
be overridden if the BCM receives a door Unlock input or a key in ignition
input.
Key Cylinder Unlock
The BCM will unlock all of the doors after detecting a door lock cylinder
switch in the Unlock position for greater than 1 second.