Power Locks: Description and Operation
POWER DOOR LOCKSPower Door Lock System
The door lock switches provide a variable amount of voltage through the Multiplexed (MUX) circuit to the BCM. Depending upon that input and various conditions that must be met (i.e. door lock inhibit, etc.), the BCM will determine the action to be taken and activate the proper relay for approximately 250 to 350 msec. If the vehicle is equipped with the vehicle theft security system it will have the central locking feature which locks and unlocks all doors from the cylinder lock switches. These switches are on separate multiplexed circuits to the BCM and have trouble codes relating to each of them.
Power Door Locks
The power lock system allows all four doors to be locked or unlocked electrically by operating the switch on either front door trim panel. The power lock system operates on non-switched battery current supplied through a fuse in the junction block so that the system remains functional, regardless of the ignition switch position.
All doors can be locked or unlocked electrically by operating the switch on either front door panel.
The rear doors can be locked or unlocked by actuation of the front door switch, or can be locked or unlocked mechanically and independently with their respective locking knobs.
The front doors can be locked or unlocked mechanically with the locking knob regardless of electrical locking and unlocking actuation with the front door knobs.
The right and left front door on all vehicles can be locked or unlocked mechanically from the outside with the key or electrically as described above. The left and right front doors can also be unlocked by actuation of the inside remote door handle.
Automatic (Rolling) Door Locks
The system includes an automatic door locking feature actuated by the Body Control Module (BCM). The vehicle is built with the system enabled.
This feature can be enabled or disabled by using either the DRB III or the customer programmable method. When enabled, the BCM will automatically lock all doors when all of the conditions below are met:
- All doors are closed
- The vehicle speed exceeds 15 ± 1 mph.
- The throttle position sensor tip-in is greater than 10 ± 2 degrees
If a door is opened and the vehicle slows to below 15 mph (24 km/h), the automatic locks will be disabled and will not not operate until all doors are closed and the speed is above 15 mph (24 km/h).
When the system is disabled, the door locks will work by use of the door lock switches only. When this system is enabled the automatic door locks will work automatically.
The BCM controls the power locks when the door lock switch is activated. If the door lock switch is pressed for longer than eight consecutive seconds, the BCM will de-energize the door lock relay.
The automatic door lock system can be enabled/disabled either by the customer or with the DRB III scan tool. Refer to the DRB III or the vehicle owners manual for enabling/disabling procedures.
The BCM will automatically re-lock all doors if the above conditions are met and if any of the doors become ajar and then closes again.
The power latches are also equipped with a thermal protection system which prevents the latches from burning out.
Central Locking
The central locking system is part of the Vehicle Theft Security System. This feature allows the doors to be locked/unlocked all at once with the turn of the key in the drivers or passengers side door.
Using the key, turn the driver's or passenger door cylinder lock to the lock position, all doors will lock. This feature operates differently on each door. Turn key in the driver's door to the unlock position once will unlock driver's door only. Turning the key a second time to the unlock position within five seconds of the first time will unlock all doors. Turn key once in the passenger's door to the unlock position will unlock all doors.
The lock/unlock operation will arm/disarm the Vehicle Theft Security System and will also activate/cancel the illuminated entry feature.
Child Protection Lock
The child protection locks are on the rear doors only. When enabled, they render the inside remote door release handles useless preventing small children the ability to open the rear doors when moving or in crowded traffic areas.
The lock when engaged, will disable the inside door handle from opening the door. The lock is part of the latch/lock assembly. The lock is engaged by moving a lever that is located on the rearward inside edge of the door.
Door Lock Inhibit
The door lock inhibit feature is designed to prevent the locking of keys in a vehicle. The drivers door cannot be locked unless the keys are removed from the ignition switch.
With the key in the ignition switch in the ON or OFF position and the driver's door open, all door lock switches are disabled and the BCM will ignore the command to lock the power door locks. The unlock switches are still functional. This protects against locking the vehicle with the keys still in the ignition. Once the key is removed, or the driver's door is closed, the Body Control Module will allow the power door locks to lock.
Fig.1 Remote Keyless Entry Transmitter:
Remote Keyless Entry
The system allows locking and unlocking of vehicle door(s), deck lid release, and panic by remote control using a hand held radio frequency transmitter to activate a radio receiver (RKE module). The vehicle must be in PARK before the trunk lid can be unlatched with the transmitter.
The receiver may receive signals from up to four transmitters. Each transmitter has its own code, and the code is programmed and stored into receiver memory If a transmitter is replaced or additional transmitters are added, the codes for all units have to be reprogrammed into the receiver memory. If a receiver module is replaced, the transmitter codes must be stored in the new receiver memory.
The RKE module now plugs into the Body Control Module which is directly connected to the junction block. With this feature, RKE can now be added to a non-equipped vehicle by installing a module. If the vehicle is equipped with the Vehicle Theft Security System (VTSS), RKE will also arm and disarm that system. A 4-button transmitter is used which provides lock, unlock, decklid release and panic features. Decklid release is only operable while the vehicle is in the PARK position. The module is capable of retaining up to 4 transmitter codes. Rolling code, which increases security, is also included in this system. If the transmitter goes out of synchronization it is easily put back in by pressing the lock button when the transmitter is within range. An external antenna has been added which plugs into the module to provide greater range. RKE will also turn ON the interior lamps when a valid unlock command is received and will extinguish the interior lamps when a lock command is received and all doors are closed.
The transmitter has four buttons for operation. They are LOCK, UNLOCK, DECK LID RELEASE, and PANIC.
- The UNLOCK button will unlock the driver's door and enable illuminated entry. Pushing and releasing the button once will unlock the driver's door. Pushing and releasing the button two times, within a five second interval, will unlock all doors.
- Upon pressing the LOCK button, the horn will sound a short CHIRP (if enabled) and flash the park lamps to notify that the all door lock signal was received and set. Illuminated entry is cancelled and the interior lamps are faded to OFF.
- DECK LID RELEASE - The Deck Lid release button changes from a default "press twice" actuation to a "press and hold" (for approximately one third of a second) default. Note that this is customer programmable to "no delay" if so desired.
- Pushing and holding the PANIC button will cause the panic alarm to sound for three minutes, until the panic button is pressed and held a second time, or the vehicle reaches a speed of 15 mph.
The receiver is capable of retaining a Vehicle Access Code (VAC) even when power is removed.
Each Remote Keyless Entry (RKE) module must have at least one and no more than four transmitters.
Decklid Release
Decklid release is now a function of the Body Control Module. Trouble codes are provided to assist in the diagnosis of this system.
Customer programmable features are: Horn chirp, one or two press decklid release, programming a new transmitter (using a previously programmed transmitter), rolling door locks, unlock on exit, and RKE lamp flash.
Horn Chirp Toggle
Once the transmitters have been programmed, the horn chirp can be enabled/disabled by sending the horn chirp toggle operation code to the Body Control Module (BCM).
This can be done using a DRB III scan tool or by the customer. The horn chirp will enter the opposite state of its current programmed state by receiving this operation code. The BCM is responsible for keeping track of the horn chirp status.