Power Locks: Description and Operation
POWER DOOR LOCK SYSTEMThe front doors, sliding door(s) and liftgate are equipped with actuator motors to lock or unlock the latch mechanisms. The door lock actuator motor is not serviced separately from the door latch, except for the sliding door(s).
The Body Control Module (BCM) locks or unlocks the doors when an actuation input signal from a door lock switch or Remote Keyless Entry Module (RKE) is received. The BCM turns ON the output drivers and provides a voltage level to the door lock motor for a specified time. The BCM locks the doors automatically when the vehicle is driven beyond the speed of 25.7 km/h (16 mph). The rolling door lock feature can be disabled if desired. All doors and liftgate can be locked or unlocked using mechanical button or key cylinder methods (Liftgate cylinder does not lock/unlock vehicle. It only unlocks the liftgate).
When the BCM receives input for a lock request from a door lock switch, RKE or cylinder lock switch (only with VTSS), it will turn the lock drivers on for a specified time of 375 msec. If the request is there beyond 375 msec, the BCM considers the door lock signal stuck. Once a door lock or unlock signal is stuck for longer than 10 seconds, the BCM will set a trouble code and the signal input is ignored until the stuck condition disappears. The door lock switches provide a variable amount of resistance thereby dropping the voltage of the multiplexed (MUX) circuit and the BCM will respond to that command.
AUTOMATIC DOOR LOCKS
This feature can be enabled or disabled by using either the DRB III or the customer programming method. When enabled all the doors will lock when the vehicle reaches a speed of 16 mph (25.7 km/h) and all the doors are closed. If a door is opened and the vehicle slows to below 16 mph (25.7 km/h), the door locks will operate again once all doors are closed and the speed is above 16 mph (25.7 km/h).
Automatic Door Lock
The vehicle comes with two options for power door locks:
- Rolling automatic lock (ENABLE), doors automatically lock at approximately at 25.7 km/h (16 mph).
- No rolling automatic lock (DISABLE), doors do not automatically lock when the vehicle is moving.
The BCM is equipped with a disable feature to stop the speed sensitive automatic door locks from functioning. The DISABLE feature can be switched ON or OFF as desired. When the system is DISABLED the door locks will operate normally, but will not lock automatically when the vehicle is rolling. When the door locks are ENABLED the door locks will automatically lock when the vehicle is moving at about 25.7 km/h (16 mph). All doors are closed, the PCM has set the "OK TO LOCK" bit, and doors were not previously locked.
Automatic Door Unlock
The doors will unlock automatically on vehicles equipped with power door locks if:
- Auto door locks feature is enabled and automatic unlock is enabled.
- The transmission was in gear and speed is above zero.
- The transmission in park or neutral and speed is zero.
- Any door (excluding liftgate) opens.
DOOR LOCK INHIBIT
The BCM cancels out the door lock switch actuation, when the key is in the Ignition Switch and either front door is open.
Pressing the key fob RKE lock/unlock under these conditions results in normal lock/unlock activation.
If the key is in the ignition, in any position, and either front door is ajar, all power door LOCK functions are disabled when activating either door lock switch. The UNLOCK functions are still functional. This protects against locking the vehicle with the keys still in the ignition. The RKE key fob will still lock the doors as usual. Also, if the Vehicle Theft Alarm (VTA) is armed, the door lock switch "UNLOCK" feature will be disabled until the vehicle is disarmed. Pressing the RKE lock/unlock button under these conditions will result in a normal lock/unlock activation.
After the key is removed from the Ignition Switch, or the doors are closed, the power door locks will operate normally.
CENTRAL LOCKING
If equipped with Vehicle Theft Security System (VTSS), all the doors can be locked with the key by using any of the door lock cylinders. Turning the key to the lock position will lock all the doors.
If equipped with Vehicle Theft Security System (VTSS), all the doors can be locked with the key by using any of the door lock cylinders. Turning the key to the LOCK position will lock all the doors.
When either of the front key cylinder switches is detected active, the BCM will activate the illuminated entry feature and the individual front doors will become mechanically unlocked. To central unlock all doors, a second transition from OFF to UNLOCK has to occur within 2 seconds of the first complete UNLOCK cycle.
To central unlock the driver door, turn the key to the rear of the vehicle. This indicates an unlock signal to the BCM. For the passenger door, turn the key toward the front of the vehicle. When either key cylinder switch is detected as active, the BCM will activate the illuminated entry feature. The individual doors will become mechanically unlocked.
To central lock the vehicle, the driver door lock cylinder is turned toward the front of the vehicle. The passenger door lock cylinder is turned toward the rear of the vehicle. When a lock input from either key cylinder is detected as active, the BCM will cancel the illuminated entry feature and perform the central lock operation.
DOOR LOCK CIRCUIT PROTECTION
The door lock system is protected by a 40 amp fuse located in the IPM. The BCM receives lock/unlock input and will turn ON the appropriate drivers and provide a voltage level to the door lock motor for a specific time. The IPM is located along the side of the vehicle battery in the engine compartment.
The BCM controls the door lock output drivers. If the door lock switch is actuated continuously for more than one second the BCM will turn the output driver OFF (the BCM would consider the switch stuck). The lock motors are protected with Positive Temperature Coefficient (PTC) device that prevents motor burn out.
REMOTE KEYLESS ENTRY SYSTEM
The Body Control Module interfaces with the RKE module via a one-way serial bus interface. The RKE module is not on the PCI bus. The RKE module sends a 0 - 5 volt pulse width signal to the BCM depending on which button on the transmitter was pressed. The BCM controls the door lock/unlock functions and the arming/disarming of the Vehicle Theft Security System (if equipped) and the activation of illuminated entry. The BCM will also send the appropriate messages to the Power Sliding Doors and Power Liftgate modules. The Integrated Power Module (IPM) activates the park lamps, headlamps, and horn for horn chirp when sent the appropriate message from the BCM as received from the RKE transmitter. When a one-button press is made for unlock, both driver side doors will unlock and the front and rear turn signals will flash. When a second press is initiated (within 5 seconds of the first) both passenger doors will unlock and all four turn signals will flash.
The RKE module is capable of retaining up to 4 individual access codes (4 transmitters). If the PRNDL is in any position except park, the BCM will ground the interface thereby disabling the RKE.
Both the 3 and 6 buttons transmitters will have 2-CR2016 batteries in series. The 2-button export transmitter will have 2-CR2016 batteries in series also but the 5-button will have one. The minimum battery life should be approximately 4.7 years based on 20 transmissions a day at 84 °F (25 °C). Using the DRB III and selecting RKE FOB Test can test the transmitter.
The RKE module can be programmed via the DRB III or the customer programming method. The BCM will only allow programming mode to be entered when the ignition is in the on position, the PRNDL is in park position, and the VTSS (if equipped) is in the disarmed mode.
Fig.1 Key Fob:
The key fob transmitter has six buttons. Three of them, LOCK, UNLOCK, and PANIC, are used to actuate parts of, and program the Remote Keyless Entry (RKE) system via the customer programming mode. It is not necessary to use the PANIC button with the DRB III scan tool mode of programming.
- LOCK: Pressing the LOCK button locks all doors and sounds horn (chirp) and arm the Vehicle Theft Security System, if equipped. The chirp verifies that the RKE receiver has sent a message to the BCM for door lock operation. If a door has not been closed before pressing the LOCK button, the vehicle may not be secured and the VTSS will not arm until the door is closed.
- UNLOCK: Pressing the UNLOCK button once will unlock the driver's side doors and activate the illuminated entry system and disarm Vehicle Theft Security System, if equipped. Pressing the UNLOCK button twice within five seconds will unlock all doors and activate the illuminated entry system.
- LEFT SLIDING DOOR: Pressing the LEFT SLIDING DOOR BUTTON opens/closes the left power sliding door remotely
- RIGHT SLIDING DOOR: Pressing the RIGHT SLIDING DOOR BUTTON opens/closes the right power sliding door remotely
- LIFTGATE: Pressing the LIFTGATE BUTTON opens/closes the liftgate remotely, if equipped.If not equipped with power liftgate, pressing the liftgate button will allow a one time 30 second access to liftgate.
- PANIC: Pressing the PANIC button sounds the horns at 1/2 second intervals, flashes the exterior lamps, and turns ON the interior lamps. The panic alarm will remain ON for three minutes, or until the PANIC button is actuated again or the ignition switch is turned to the RUN position.
The Remote Keyless Entry Module is capable of retaining the transmitter Vehicle Access Code(s) (VAC) in its memory even after vehicle power has been interrupted.
NOTE: Additional features available to the customer are described in the Vehicle Owners Manual.
The RKE system activates the optional memory seat, mirror system and adjustable pedals, if equipped. Two primary key fob transmitters can be programmed to actuate memory seat and mirror setting 1 or 2. Two additional key fob transmitters can be added, but they will not be able to operate the memory seat and mirror system (Refer to ELECTRICAL/POWER SEATS - OPERATION) and (Refer to ELECTRICAL/POWER MIRRORS - OPERATION).
DOOR CYLINDER LOCK SWITCH
The Door Cylinder Lock Switch is used to:
- Unlock/Lock all the doors via the Central Locking feature.
- Arm/Disarm the Vehicle Theft Security System.
- Trigger the Illuminated Entry feature.
The door cylinder lock switch is mounted to the rear of the driver and passenger door lock cylinders. When installed on the rear of the cylinder, there is a tab on the lock cylinder that aligns with the switch to prevent it from turning. An anti-rotating device. The door cylinder lock switch is a one time use switch. Once it is removed from the rear of the door lock cylinder, it may not be reinstalled and a new switch must be used.
When the Door Cylinder Lock Switch is turned either way using the door key cylinder, the BCM reads a direct message signal from the switch, via the Programmable Communication Interface (PCI) bus.
If turning the key cylinder once, toward the front of the vehicle (for either driver or passenger doors), this will:
1. Mechanically unlock the door lock.
2. Disarm the Vehicle Theft Security System (if equipped).
3. Turn ON the Illuminated Entry (if equipped) for approximately 30 seconds.
If the key cylinder is turned to the unlock position (toward the front of vehicle) twice within two seconds, all the doors and liftgate will unlock (if equipped with the central locking feature).
To lock the vehicle using the door cylinder lock switch, turn the key cylinder toward the rear of the vehicle (either passenger or driver doors) once. This will lock the door that you are using the key on. If equipped with the central locking feature, this will lock all the other doors and liftgate. Furthermore, this will arm the vehicle theft security system and turn OFF the illuminated entry.
REMOTE KEYLESS ENTRY MODULE
The RKE module is capable of retaining up to four different Vehicle Access Codes.
Whenever the vehicle battery power is interrupted the RKE Module will retain all vehicle access codes in its memory. When replacing or adding a key fob transmitter (maximum 4) a DRB III scan tool is required to program the RKE Module to accept the new Vehicle Access Code if a customer owned transmitter is not available. Refer to Electrical, Remote Keyless Entry Module, Standard Procedure - Programming RKE Module or the Proper Body Diagnostic Procedures manual.