Keyless Entry: Description and Operation
Keyless Entry System Description and Operation
The keyless entry system is a vehicle entry device. The keyless entry system is used in conjunction with the body control module (BCM) to remotely activate certain vehicle features. Keyless entry will lock/unlock the doors, or release the rear compartment lid when a corresponding button on the keyless entry transmitter is pressed. This is accomplished by the transmitter sending a radio frequency to the remote control door lock receiver (RCDLR). The RCDLR interprets the signal and activates the requested function via a serial data message to the BCM. A low transmitter or vehicle battery or radio frequency (RF) interference from aftermarket devices, such as 2-way radios, power inverters, computers, etc., may cause a system malfunction. High RF traffic areas may also cause interference that could lead to a malfunction. Keyless entry allows you to operate the following components:
* Door locks
* Rear compartment lid release
* Remote vehicle starting, if equipped
The keyless entry system has the following components:
* Keyless entry transmitters
* Keyless entry antenna
* BCM
* RCDLR
Keyless Entry Transmitters
The keyless entry transmitters are used to lock and unlock the vehicle door while away from the immediate area of the vehicle. Vehicles without remote vehicle start will operate at a distance of up to 20 m (65 ft) away. Vehicle with remote vehicle start will operate at a distance of up to 60 m (195 ft) away. Up to 4 transmitters may be programmed to a single vehicle.
Keyless Entry Antenna
The keyless entry antenna is used to receive radio frequency (RF) communications sent by the keyless entry transmitters. The keyless entry antenna also receives RF signals from the tire pressure monitoring (TPM) sensors located at each wheel.
A coax antenna lead connects the antenna to the remote control door lock receiver (RCDLR). When a transmitter button is present, the RF signal sent by the transmitter is received by the antenna and the communications are inputted to the RCDLR.
Remote Control Door Lock Receiver (RCDLR)
The remote control door lock receiver (RCDLR) is a multifunction module that operates both the keyless entry system as well as the TPM system. When an RF message is received from a keyless entry transmitter, the RCDLR interprets this signal and will request via serial data that the body control module (BCM) perform the specific function, i.e. door lock, door unlock, or vehicle locate.
Two Stage Unlocking - Disabled
Momentarily press the transmitter UNLOCK button in order to perform the following functions:
* Unlock all vehicle doors
* Illuminate the approach lighting, if enabled through personalization
* Flash the turn indicators, if enabled through personalization
* Disarm the Content Theft Deterrent (CTD) System, if equipped
* Deactivate the CTD system when in the alarm mode
Two Stage Unlocking - Enabled
First UNLOCK Button Press
Momentarily press the transmitter UNLOCK button in order to perform the following functions:
* Unlock the front vehicle doors
* Illuminate the approach lighting, if enabled through personalization
* Flash the turn indicators, if enabled through personalization
* Disarm the Content Theft Deterrent (CTD) System, if equipped
* Deactivate the CTD system when in the alarm mode
Second UNLOCK Button Press
Momentarily press the transmitter UNLOCK button a second time in order to perform the following functions:
Unlock the rear vehicle doors
Lock All Doors
Press the transmitter LOCK button to perform the following functions:
* Lock all vehicle doors
* Immediately turn OFF the interior lamps
* Flash the exterior lights, if enabled through personalization
* Arm the CTD system, if equipped
Rear Compartment Lid Release
Press the transmitter rear compartment lid release button to perform the following function:
Open the rear compartment lid
Remote Vehicle Start (RVS) - if equipped
The remote vehicle start (RVS) function allows engine starting while not in the vehicle. It also allows the vehicle HVAC system and other vehicle systems to enable, providing a comfortable vehicle upon entry. RVS functions have an operating range of up to 195 feet, depending on conditions. The RVS sequence begins by pressing and releasing the lock button and then pressing and holding the RVS buttons on the keyless entry transmitter. The turn signal lamps will illuminate to indicate the vehicle has received the remote start request. Each time an RVS is performed, the vehicle doors are locked, however they may then be unlocked/locked with the transmitter or vehicle key at any time. Once activated, the engine is allowed to run for 10 minutes. The RVS time may be extended by an additional 10 minute by again pressing and releasing the lock button and then pressing and holding the RVS buttons on the transmitter. This feature is called a RVS continue and allows a maximum of 20 minutes of engine running. If the RVS continue is performed at 7 minutes into the initial 10 minute time-out, a total of 17 minutes of engine running would occur. The RVS event may be suspended at any time by pressing only the RVS button on the transmitter or by entering the vehicle and turning ON the hazard lamps.
In between ignition cycles, only two RVS events may occur or be attempted. Once two events or attempts have been made, future RVS events will be suspended until the vehicle is started using the ignition.
Enable/Disable RVS
Using the driver information center (DIC), RVS may be enabled or disabled as a part of vehicle personalization. Refer to the vehicle owners manual for more information.
Hood Ajar Switch
The hood switch provides status of the hood to the BCM for RVS purposes. The switch is integrated into the hood latch assembly. The hood ajar switch provides 2 separate inputs to the BCM. These separate inputs allow the BCM to actively monitor for a hood ajar switch fault.
RVS Circuit Description
The RCDLR receives a signal from the keyless entry transmitter indicating a RVS request. A message is then sent to the BCM which determines if a crank request message will be sent to the ECM to allow engine starting. To determine if conditions are correct for an RVS event, the BCM will ensure the following conditions are met:
* All vehicle doors are closed
* A valid hood ajar switch closed signal is present
* The doors are locked
* The hazard switch is OFF
* The vehicle power mode is correct
* No content theft deterrent (CTD) alarm triggers are present
* The vehicle is not in valet mode (if equipped)
When the BCM determines all conditions meet those required for an RVS event, a message is sent via serial data to the ECM. The ECM relies on the RVS message from BCM to enable RVS when the crank request signal is received. If the ECM does not receive a valid RVS message, it will not attempt to start the engine. While the ECM is in RVS mode it will suspend engine operation if any of the following additional conditions occur:
* Vehicle speed is greater than 0
* Transmission is not in PARK
* Excessive engine coolant temperature
* Low oil pressure
* The malfunction indicator lamp (MIL) is commanded ON
* Engine crank time is greater than 30 seconds
* Excessive engine speed
* Accelerator pedal position too high
* Remote start timer equals 0
* Immobilizer system indicates tamper
Keyless Entry Personalization
Vehicle lock/unlock functions and remote vehicle start (RVS) settings may be personalized. For functional descriptions and personalization instructions, refer to the vehicle owners manual.
Rolling Code
The Keyless Entry System uses rolling code technology. Rolling code technology prevents anyone from recording the message sent from the transmitter and using the message in order to gain entry to the vehicle. The term "rolling code" refers to the way that the Keyless Entry System sends and receives the signals. The transmitter sends the signal in a different order each time. The transmitter and the remote control door lock receiver (RCDLR) are synchronized to the appropriate order. If a programmed transmitter sends a signal that is not in the order that the RCDLR expects, then the transmitter is out of synchronization. This occurs after 256 presses of any transmitter button when it is out of range of the vehicle.
Automatic Synchronization
The keyless entry transmitters do not require a manual synchronization procedure. If needed, the transmitters automatically re-synchronize when any button on the transmitter is pressed within range of the vehicle. The transmitter will operate normally after the automatic synchronization.