Keyless Entry System Description and Operation

Keyless Entry System Description and Operation – Active The keyless entry system is a vehicle entry device. The keyless entry system is used in conjunction with the door locks to unlock the vehicle. Keyless entry will lock/unlock a door or open 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 that has a direct link to the body control module (BCM). The BCM interprets the signal and activates the requested function or requests the appropriate ECU to activate the function via a serial data message. A low transmitter battery or radio frequency interference from aftermarket devices, such as 2-way radios, power inverters, computers, etc., may cause a system malfunction. High radio frequency traffic areas, such as gas stations that use pay-at-the-pump radio frequency transponders, may also cause interference that could lead to a malfunction. Keyless entry allows you to operate the following features: Door lock/unlock Rear compartment lid release Illuminated entry lamps Panic alarm/vehicle locator Remote vehicle start Passive keyless entry able/disable Automatic window express down, if equipped Automatic window express up, if equipped Automatic power mirror folding/unfolding, if equipped Keyless Entry System Description and Operation – Passive Passive keyless entry allows entry to a locked vehicle without pressing any buttons on the keyless entry transmitter. The passive entry system uses low frequency antennas in several different areas on the vehicle to determine the location of the transmitter. When passively opening a locked door or the rear compartment, you must have a programmed transmitter with you in your pocket, purse, or briefcase within a one meter range. When an exterior door handle button is pressed or the rear compartment touch pad is pressed, the body control module activates the low frequency antenna which sends out a challenge to the keyless entry transmitter. Because of the low frequency, communication range is limited. The antenna will emit the challenge in a one meter range. The transmitter must be within this range to receive the challenge. The transmitter receives this challenge and emits it’s response as an RF message, which is received by the remote control door lock receiver. If the response is correct, entry into the vehicle will be allowed. As a customer convenience feature, the keyless entry system will notify the driver if the transmitter has been left in the vehicle after exiting by chirping the vehicle horn three times and displaying a message on the DIC. This may be turned off using vehicle personalization. Also, if the transmitter is left in the vehicle after the central door lock switch has been used to lock the vehicle, the driver door will remain unlocked after exiting the vehicle. This is intended to prevent locking the transmitter in the vehicle and being unable to access it. Keyless Entry System Description and Operation – Keyless Start The keyless start portion of the keyless entry system allows vehicle starting, having only the transmitter as your key. The keyless start system uses low frequency antennas in three different locations on the vehicle to determine the location of the transmitter. Multiple antenna are used to ensure complete coverage of the vehicle interior and rear compartment. When using the keyless start system, a programmed transmitter must be in the vehicle’s interior, in the driver’s pocket, purse, or briefcase. When the ignition mode switch is pressed, the low frequency antennas emit a challenge to the keyless entry transmitter. The transmitter receives this challenge and emits it’s response as an RF message, which is received by the remote control door lock receiver. If the response is correct, vehicle starting will be allowed. If RF communication is interrupted, a “No Remote Detected” message will be displayed on the DIC. In these cases, the transmitter can be placed in the transmitter pocket located in the center console. The immobilizer antenna coil is located directly beneath the transmitter pocket. Placing the transmitter in the pocket will create a low powered coupling between the transmitter and immobilizer antenna, allowing communications to occur and enabling vehicle starting. If the key has been idle the DIC may display “Key In Sleep Mode, Move Key, Then Start”. In this case move the vehicle key to start the vehicle. The keyless entry system has the following components: Keyless entry integrated key/transmitter Driver and passenger side antennas Driver and passenger door handle switches (part of the door handle assembly) Rear fascia antenna Immobilizer antenna coil (front console antenna function) Rear console antenna Trunk antenna (rear compartment) Body control module (BCM) Remote control door lock receiver Keyless Entry Transmitters By operating any of the exterior door handle buttons or the start/stop switch, a nearby transmitter is challenged by a keyless entry antenna. The transmitter will send an RF response to the remote control door lock receiver, which communicates with the BCM. The BCM will interpret this communication and either allow or deny vehicle entry or starting. Side Antennas The keyless entry side antennas are used to transmit low frequency communications to the keyless entry transmitters. The keyless entry side antennas are located in the driver and passenger body sides. The antennas are controlled by the body control module. When the exterior door handle button is pressed, the respective antenna will send out a challenge to the keyless entry transmitter, which begins the passive entry communications. Rear Fascia Antenna The rear fascia antenna is used to transmit low frequency communication to the keyless entry transmitters for entry to rear compartment. The rear fascia antenna is located behind the rear fascia. The antenna is controlled by the body control module. When the rear compartment touch pad is pressed, the antenna sends out a challenge to the keyless entry transmitter, which begins the passive entry communications. Immobilizer Coil Antenna This antenna is located in the front of the center console. The Immobilizer antenna coil is used for vehicle starting functions and for learning vehicle keys. When the ignition mode switch is pressed, the antenna is energized or “pinged”. This emits a low frequency challenge signal that is received by the keyless entry transmitter. The transmitter will then reply to this challenge with a response and, if correct, vehicle starting will occur. If the transmitter battery is dead, weak, or the RF signal is being interrupted, the transmitter may be placed in the pocket to create a low powered coupling between the transmitter and immobilizer coil antenna, allowing communications to occur and enabling vehicle starting. Rear Console Antenna This antenna is located in the rear of the center console. The rear console antenna is used for vehicle starting functions. When the ignition mode switch is pressed, the antenna is energized or “pinged”. This emits a low frequency challenge signal that is received by the keyless entry transmitter. The transmitter will then reply to this challenge with a response and, if correct, vehicle starting will occur. Rear Compartment Antenna This antenna is located near the center of the rear compartment area. The rear compartment antenna is used for vehicle starting functions. When the ignition mode switch is pressed, the antenna is energized or “pinged”. This emits a low frequency challenge signal that is received by the keyless entry transmitter. The transmitter will then reply to this challenge with a response and, if correct, vehicle starting will occur. OnStar® Remote Link A vehicle operator may have the ability to perform some of the keyless entry functions using applications on personal devices such as smart phones. Refer to OnStar Description and Operation. Body Control Module (BCM) The BCM is a multi-function module that performs the following functions: Receive and authenticate active transmitter and keyless start/entry signals from the remote control door lock receiver Determines the function requested by the transmitter signal Performs the function requested by the transmitter signal Activating vehicle antennas for passive keyless entry functions Activating vehicle antennas for keyless start functions Backup control for the ECM accessory wakeup and the run/crank relay If equipped, controls the electronic steering column lock Receiver of the exterior door handle switch inputs and door open switch (not the door ajar switch) Ignition mode switch monitoring Unlock Driver Door Only – Active Momentarily press the transmitter UNLOCK button in order to perform the following functions: Unlock only the driver door or all doors, if enabled through personalization Illuminate the interior lamps for a determined length of time, or until the ignition is turned ON Flash the exterior lights, if enabled through personalization Disarm the Content Theft Deterrent (CTD) system Deactivate the CTD system when in the alarm mode Unlock All Doors – Second Operation – Active Momentarily press the transmitter UNLOCK button a second time, within 5 seconds of the first press, to perform the following function: Unlock the remaining doors Unlock Driver Door Only – Passive If enabled through personalization, approach the driver door with a valid keyless entry transmitter and press the door handle button to perform the following functions: Unlock and open only the driver door Disarm the CTD system, if equipped Deactivate the CTD system when in the alarm mode Unlock All Doors – Passive Approach any non driver door (front or rear) or, if enabled through personalization, the driver door with a valid keyless entry transmitter and press the door handle button to perform the following functions: Unlock all vehicle doors Disarm the CTD system, if equipped Deactivate the CTD system when in the alarm mode Lock All Doors – Active 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 Chirp the horn, if enabled through personalization Arm the CTD system Lock All Doors – Passive Exit the vehicle (with ignition off) with the keyless entry transmitter to automatically perform the following functions, if equipped. Lock all vehicle doors after a delay Flash the exterior lights, if enabled through personalization Chirp horn, if enabled through personalization Arm the CTD system When all doors are closed, they can also be locked from the exterior by operating a front door handle button or touch pad while having a valid transmitter within range. Vehicles equipped with a rear door button can also lock all doors from the rear doors. Rear Compartment Lid Release – Active If the vehicle transaxle is in PARK or NEUTRAL, a double press of the transmitter rear compartment release button will open the rear compartment lid. Rear Compartment Lid Release – Passive Approach the rear of a locked vehicle with a valid keyless entry transmitter. Press the rear compartment lid release touch pad. The rear compartment lid will open. Vehicle Locator/Panic Alarm/Active A single press of the panic button performs the following functions. Some functions may be dependent on personalization settings: Pulses the horn three times Flashes the exterior lamps three times A press and hold of the panic button performs the following functions: Pulses the horn and flashes the parking lamps for 30 second or until the following conditions occur: – The panic button is pressed – The ignition switch is turned to the RUN position with a valid key Remote Vehicle Start/Active The remote vehicle start 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. The remote vehicle start sequence begins by pressing and releasing the remote vehicle start button on the keyless entry transmitter twice. The turn signal lamps will illuminate to indicate the vehicle has received the remote start request. Each time a remote vehicle start is performed, the vehicle doors are locked, however they may then be unlocked/locked with the transmitter at any time. Once activated, the engine is allowed to run for 15 minutes. The remote start operation can be repeated as many times as desired up to a total run time of 30 minutes. The remote vehicle start event may be cancelled at any time by pressing only the remote vehicle start button on the transmitter or by entering the vehicle and turning ON the hazard lamps. Hood Ajar Switch/Active The hood switch provides status of the hood to the BCM for remote vehicle start 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. Remote Vehicle Start Circuit Description/Active The BCM receives a signal from the keyless entry transmitter indicating a remote vehicle start request. The BCM and ECM use the following inputs to verify the system is ready to enable a remote vehicle start event: Vehicle is not in valet mode Vehicle is in park Keyless entry transmitter is not in the vehicle The hood is closed The hazard switch is OFF Vehicle power mode is OFF The malfunction indicator lamp (MIL) is not commanded ON by the ECM Remote start timer does not equal 0 (the 30 minute maximum time has not been used) When the BCM determines all conditions meet those required for a remote vehicle start event, a message is sent via serial data to the ECM. While the ECM is in remote vehicle start mode it will cut fuel to the engine if any of the following monitored conditions occur: Vehicle speed is greater than 0 Transmission is not in P Excessive engine coolant temperature Low oil pressure Engine crank time is greater than 30 seconds Excessive engine speed Accelerator pedal position too high Immobilizer system indicates a theft attempt If any conditions prevent a remote start or cause a remote start operation to be cancelled there is a record of the cause in the scan tool. Keyless Entry Personalization Vehicle lock/unlock functions and remote vehicle start settings may be personalized for the vehicle. This includes the capability of turning the passive entry system completely off. For functional descriptions and programming instructions, refer to the vehicle owners manual.