Power Door Locks
The power door locks system consists of the following components:
| • | Body control module (BCM) |
| • | Driver door lock switch |
| • | Front passenger door lock switch |
| • | Driver lock cylinder switch |
| • | Door lock actuators in each of the doors |
| • | DR LK/TRUNK 15-amp fuse |
For door lock operation, the instrument panel (I/P) fuse block supplies battery
positive voltage, through the 15-amp DR LK/TRUNK fuse, to the BCM. The BCM uses this
circuit exclusively to apply power to the door lock actuators. The BCM is also supplied
a ground circuit from G301, which it uses to ground the door lock actuators. When
a door lock switch is activated , the BCM internally connects these 2 circuits
to the appropriate lock and unlock control circuits to actuate the locking or unlocking
functions.
Power Door Lock Controls
The power door lock system is controlled by the BCM and can be activated by
anyone of the following:
| • | A door lock switch LOCK or UNLOCK actuation |
| • | A door lock cylinder switch LOCK/UNLOCK actuation |
| • | A keyless entry transmitter actuation |
| • | An OnStar® UNLOCK actuation |
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 battery
positive voltage. The door lock actuators transition to the LOCK position. The lock
actuator unlock control circuits are grounded within the BCM.
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 battery positive voltage. The driver door lock actuator transitions to the UNLOCK
position. The lock actuator unlock control circuits are grounded within the BCM. 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 battery
positive voltage. The passenger door lock actuators transition to the UNLOCK position.
The lock actuator unlock control circuits are grounded within the BCM. When the keyless
entry transmitter is used to unlock the passenger doors, the BCM requires a repeated
unlock command before it performs the unlock function. However, when the unlock input
is from a door lock switch, a single unlock command is all that is required to unlock
all doors.
Automatic Door Lock/Unlock
The automatic door lock or unlock function is a vehicle personalization feature
with the following 4 programmable modes of operation:
| • | The automatic door lock feature is disabled. |
| • | All of the doors lock when the vehicle is shifted 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 with the key out of the ignition. |
| • | All of the doors lock when the vehicle is shifted 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.
Auto Door Relock
Auto door relock is enabled if the doors are opened and closed or the power
door lock switch is activated to unlock the doors. The doors will relock when the
vehicle speed is greater then 5 mph.
Lockout Prevention
This function is intended to prevent the vehicle operator from locking the doors
if the key is left in the ignition. 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 cancelled if the BCM receives
a door unlock input, a key in ignition input or if the lock button is pressed twice.
Key Cylinder Lock
The BCM will lock all of the doors immediately upon detecting a door lock cylinder
switch in the LOCK position. The BCM supplies battery positive voltage, through the
door lock key switch lock signal circuit, to the door lock cylinder switch. The door
lock cylinder switch is grounded at G301 for the driver door lock switch and at G302
for the passenger door lock. When the door lock cylinder switch is activated to the
LOCK function, the normally open contacts of the two circuits are closed, and the
BCM interprets the voltage signal as a lock doors 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. The BCM supplies battery
positive voltage, through the door lock key switch unlock signal circuit, to the door
lock cylinder switch. The door lock cylinder switch is grounded at G301 for the driver
door lock switch and at G302 for the passenger door lock. When the door lock cylinder
switch is activated to the UNLOCK function, the normally open contacts of the two
circuits are closed, and the BCM interprets the voltage signal as a unlock doors input.
