Keyless Entry: Description and Operation

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 (RCDLR). The RCDLR interprets the signal and activates the requested function via a serial data message. A low transmitter 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, such as gas stations that use pay-at-the-pump RF transponders, may also cause interference that could lead to a malfunction. Keyless entry allows you to operate the following components:
- The door locks
- The rear compartment lid release
- The illuminated entry lamps

The keyless entry system has the following components:
- The #1-#4 keyless entry transmitters
- The headliner and console antennas
- The console active antenna
- The instrument panel module (IPM)
- The RCDLR

KEYLESS ENTRY TRANSMITTERS
The keyless entry transmitter are used to passively or actively lock and unlock the vehicle.

When any one of the 4 allowable programmed transmitters are challenged by a keyless entry antenna by operating either of the front exterior door handles, they will passively send a radio frequency (RF) signal to the remote control door lock receiver (RCDLR) via the door antennas; the RCDLR will then interpret this communication and either allow entry into the vehicle or deny it.

KEYLESS ENTRY DOOR ANTENNAS
The keyless entry door antennas are used to transmit and receive radio frequency (RF) communications with the keyless entry transmitters.

The keyless entry door antennas are molded into the vehicles front left and front right exterior door handles. The antennas are serviced as part of the door handle assembly. The antennas are controlled by the remote control door lock receiver (RCDLR). When the exterior door handle is operated, the respective antennas sends out sends out a challenge to the keyless entry transmitter which begins the passive entry communications.

HEADLINER AND CONSOLE ANTENNAS
The keyless entry headliner and console antennas have a dual purpose. The antennas are used for both keyless entry and vehicle theft deterrent functions. In their keyless entry function, they are used to locate any keyless entry transmitters within the vehicle. In the antennas theft deterrent functions, they transmit and receive the needed communications with the keyless entry transmitter to enable vehicle starting.

The keyless entry headliner antenna is located under the vehicles headliner. The console antenna is located in the vehicle center console. The use of two antennas and the placement of the antennas is to ensure complete coverage of the vehicle interior. The antennas are controlled by the remote control door lock receiver (RCDLR). These antennas share a driver and are controlled simultaneously by the RCDLR. When the start button is pressed, both antennas send out an identical challenge to the keyless entry transmitter.

CONSOLE ACTIVE ANTENNA
The keyless entry console active antenna is located in the center console. It has a small pocket next to it where the key fob can be inserted if the key fobs battery is dead, weak or the radio frequency (RF) signal is being interrupted.

The purpose of the console active antenna is to send a low frequency RF challenge to a programmed key fob when the start button is pressed. The console active antenna is controlled by the remote control door lock receiver (RCDLR).

REMOTE CONTROL DOOR LOCK RECEIVER (RCDLR)
The remote control door lock receiver (RCDLR) is a multi-function module located in the upper passenger side of the dash panel. The RCDLR can be accessed by removing the upper dash pad. The RCDLR controls all the vehicles antennas for passive and active keyless entry, as well as vehicle theft deterrent and vehicle starting. The RCDLR will send an AC voltage signal and provide ground to the door handle antennas. This will enable the antennas to send out the low frequency broadcast challenge to a key fob in range.

KEYLESS ENTRY SYSTEM DESCRIPTION AND OPERATION - PASSIVE
The passive keyless entry allows you to enter a locked vehicle without pressing any button on the keyless entry transmitter. You must only have the transmitter with you. This passive system is also part of the vehicle starting system. It allows you to start and run the vehicle having only the transmitter as your key. The passive entry and starting system use low frequency antennas in 5 different areas on the vehicle to determine the location of the key fob to the vehicle. When passively opening a locked door, or a rear compartment lid, you must have a programed key fob with you in your pocket, purse, or briefcase. As a customer opens the door handle or rear compartment open pad, the low frequency antenna sends out a challenge to the keyless entry transmitter. The transmitter must be in a one meter range of the door or rear compartment lid that the customer is opening in order to receive the challenge. If the challenge from the low frequency antenna is met, the transmitter will respond, allowing the door to be unlocked and opened. Starting the vehicle also works in the same manner. The key fob must be within the passenger compartment of the vehicle when the Start/ACC/OFF button is pressed. The low frequency antenna sends a challenge to the transmitter and if the challenge is met, the transmitter will respond to the remote control door lock receiver (RCDLR). The RCDLR will then send out a fuel enable password to the engine control module (ECM). As long as all security requirements are met, and the ECM receives the password over the serial data line, the engine will start and run. A low transmitter 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, such as gas stations that use pay-at-the-pump RF transponders, may also cause interference that could lead to a malfunction.

The passive keyless entry has the following components:
- The keyless entry transmitters (up to 4 total)
- The RCDLR
- The LH door handle antenna, located within the LH front exterior door handle
- The RH door handle antenna, located within the RH front exterior door handle
- The console antenna, located in the passenger area, within the center console
- The headliner antenna, located in the passenger area, beneath the headliner
- The trunk antenna, located in the rear compartment area near the rear compartment lid latch
- The console active antenna, located inside the passenger compartment, within the center console

STARTING THE VEHICLE/ACC MODE
To start a vehicle you must have a valid keyless entry transmitter present within the passenger compartment of the vehicle, the brake pedal depressed, and the transmission in Park or Neutral. If there are no problems with key fob detection, the vehicle will be able to be started, or put into accessory mode, when the Start/ACC/OFF mode button is pressed. If a key fob is not detected, or the radio frequencies are being interrupted, a message will display on the driver information center (DIC) stating, NO FOB DETECTED. A NO FOB DETECTED message may be caused by a low transmitter battery or radio frequency (RF) interference from aftermarket devices, such as 2-way radios, power inverters, computers, etc. High RF traffic areas, such as gas stations that use pay-at-the-pump RF transponders, may also cause interference. A NO FOB DETECTED message caused by an aftermarket device or high RF traffic is considered normal and does not require the replacement of any components. Replacing components in these situations will typically not increase the performance of the system. Simply moving the fob to a different location inside the vehicle may allow key fob communication to continue. If moving the key fob within the vehicle does not correct the message, a pocket is located in the center console for the key fob to slide into. The key fob must be inserted into the pocket with the buttons facing toward the front of the vehicle. With the key fob inserted into the pocket correctly, a low frequency coupling will occur between the key fob and the console active antenna when the Start mode or ACC/OFF mode button is pressed. This will allow the vehicle to be operated in a normal fashion.

VEHICLE ON ENGINE OFF MODE
This mode is used to have all modules powered up and communicating on the serial data line. In order to achieve this mode the customer must have a valid keyless entry transmitter within the passenger compartment of the vehicle and the transmission in Park or Neutral. Once that criteria is met, the customer must press and hold the ACC/OFF portion of the Start/ACC/OFF mode button for 5 seconds. The vehicle will power up with the engine OFF. A low transmitter 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, such as gas stations that use pay-at-the-pump RF transponders, may also cause interference that could lead to a malfunction.

TURNING OFF THE VEHICLE
When a vehicle is in a normal run mode, the keyless entry transmitter should already be present within the passenger compartment. To switch the vehicle to OFF mode, press the ACC/OFF portion of the Start/ACC/OFF mode button and the vehicle will power OFF. For a vehicle to transition to the OFF mode the transmission must be placed in Park. If the transmission is not in Park when the vehicle is switched OFF, the ignition will remain in the RUN position. Should this occur, the vehicle will automatically switch to the OFF mode after approximately 10 minutes.

While in normal run mode if the transmitter is removed from the vehicle it will not stall; the vehicle will continue to run as normal. However, if the vehicle is attempted to be powered OFF with no key fob present, the driver information center (DIC) will display a message to the customer stating NO FOB, OFF or RUN. At this point, the customer has a final opportunity to continue to run the vehicle. Once a running vehicle is powered OFF without a key fob present, the vehicle will not be able to be restarted until a valid key fob is present. On a normal power OFF, if the customer is exiting the vehicle, and the key fob is left in the passenger compartment, the horn will chirp 3 times, alerting the customer that the key fob has been left in the vehicle. This feature can be turned On/Off through the DIC personalization. Refer to Personalization Description and Operation in Personalization.

UNLOCK DRIVER DOOR ONLY - ACTIVE
Momentarily press the transmitter UNLOCK button in order to perform the following functions:
- Unlock only the driver door.
- Illuminate the interior lamps for a determined length of time, or until the ignition is turned ON.
- Flash the exterior lights, if selected ON in personalization.
- Disarm the Content Theft Deterrent (CTD) System, if equipped.
- 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 4 seconds of the first press, to perform the following functions:
Unlock the remaining doors.

UNLOCK FRONT DOOR ONLY - PASSIVE

IMPORTANT: This feature can be turned ON or OFF through vehicle personalization. Refer to Vehicle Personalization (w/o Voice Recognition) Vehicle Personalization (w/Voice Recognition) in Personalization.

Approach either front door with a valid keyless entry transmitter to perform the following functions:
- Unlock only the approached door when door handle is operated.
- Disarm the Content Theft Deterrent (CTD) System, if equipped.
- Deactivate the CTD system when in the Alarm Mode.

UNLOCK ALL DOORS - PASSIVE

IMPORTANT: This feature can be turned ON or OFF through vehicle personalization. Refer to Vehicle Personalization (w/o Voice Recognition) Vehicle Personalization (w/Voice Recognition) in Personalization.

Approach either front door with a valid keyless entry transmitter to perform the following functions:
- Unlock all vehicle doors when the approached door handle is operated.
- Disarm the Content Theft Deterrent (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 selected ON in personalization.
- Chirp the horn, if selected ON in personalization.
- Arm the Content Theft Deterrent (CTD) System.

LOCK ALL DOORS - PASSIVE
With passive locking enabled in the driver information center (DIC) personalization, exit the vehicle with the keyless entry transmitter to perform the following functions:
- Lock all vehicle doors.
- Flash the exterior lights, if selected ON in personalization.
- Chirp horn, is selected ON in personalization.
- Arm the Content Theft Deterrent (CTD) System.

If 2 keyless entry transmitters are within a vehicle and a single transmitter exits, the transmitter left within the vehicle will be ignored and the vehicle will be locked as normal. The transmitter left inside the passenger compartment will be ignored until a valid transmitter unlocks the vehicle again.

REAR COMPARTMENT LID RELEASE - ACTIVE
If the vehicle transaxle is in PARK or NEUTRAL and the ignition is in the OFF position, a single press of the transmitter rear compartment release button will open the rear compartment lid.

REAR COMPARTMENT LID RELEASE - PASSIVE
Approach the rear of the vehicle with a valid keyless entry transmitter. Push the rear compartment open pad. The rear compartment lid will open and raise.

Any keyless entry transmitter left inside the truck will allow the trunk to be reopened at any time. This feature will not allow a customer to lock the transmitter in the trunk.

REMOTE VEHICLE START (RVS)
To operate the function, first press and release the lock button on the keyless entry transmitter, then immediately press the remote vehicle start (RVS) button for 2 seconds. The vehicle park lamps will be illuminated to indicate that the engine is running. The RVS function is allowed to start the vehicle 2 times for 10-minute intervals. If the remote control door lock receiver (RCDLR) receives a second request for an RVS event while already operating in RVS, then the first timer times out and then the second timer starts. If the RVS button was pressed for the first time, then 7 minutes later the RVS button was pressed a second time, the total time for the RVS event would be 17 minutes. When the RVS button is pressed for the second time, the first 10-minute interval automatically stops and the RCDLR starts counting the second 10-minute interval. After the first event times out, 10 minutes, the second event must be requested within 20 minutes, or the function is disabled.

RVS can be deactivated by pressing the RVS button on the keyless entry transmitter, pressing the hazard switch, or by pressing the ACC/OFF portion of the Start/ACC/OFF mode button. There are also other safety and security measures that will deactivate RVS, these include depressing the accelerator pedal or opening the hood. RVS may not function when DTCs are set. In these instances, the park lights will flash once when the RVS signal is received by the RCDLR, but the vehicle will not start. If the vehicle is put into valet mode by pressing the valet switch, RVS will also be disabled.

RVS is designed to transition for RVS to normal engine run operation without any apparent change to the customer except entering the vehicle with a valid keyless entry transmitter and pressing the START button.

While in RVS mode all modules that are powered by the Run/Crank relay shall be active and understand that RVS is active. All on-board diagnostics (OBD) II functions shall also be active.

The RVS feature can be turned off through personalization on the DIC. Other RVS features may also be turned on or off via personalization. These include HVAC operation, rear defogger operation, and heated/ventilated seat operation. Refer to Vehicle Personalization (w/o Voice Recognition) Vehicle Personalization (w/Voice Recognition) in Personalization.

DISABLE RVS
To disable the remote vehicle start (RVS) function, perform the following steps:
1. Turn ON the ignition, with the engine OFF.
2. Access the RVS personalization features within the driver information center (DIC).
3. Disable the RVS feature.

The current state of RVS can be viewed through the DIC display under the Remote Start the display will read either enabled or disabled.

When valet mode is enabled by pressing the valet switch, RVS operation will be disabled.

ENABLE RVS
To enable the remote vehicle start (RVS) function, perform the following steps:
1. Turn ON the ignition, with the engine OFF.
2. Access the RVS personalization features within the driver information center (DIC).
3. Enable the RVS feature.

The current state of RVS can be viewed through the DIC display under the Remote Start the display will read either enabled or disabled.

HOOD AJAR SWITCH
The hood switch provides status of the hood to the rear integration module (RIM) for remote RVS functions. It is integrated into the hood latch assembly. The hood ajar switch provides 2 separate inputs to the RIM. When the hood is closed, the hood open switch signal circuit is approximately battery voltage and the hood closed switch signal circuit is open. When the hood is opened, the hood open switch signal circuit is open and the hood closed switch signal circuit is approximately battery voltage.


CIRCUIT DESCRIPTION(RVS)
The remote control door lock receiver (RCDLR) receives a signal from the keyless entry transmitter indicating a remote vehicle start (RVS) request. A message is then sent to the instrument panel module (IPM) which determines if a crank request message will be sent to the engine control module (ECM) to activate RVS. To determine if conditions are correct for an RVS event, the IPM will request information from the rear integration module (RIM). The IPM looks at the following inputs:
- Vehicle is not in valet mode.
- All vehicle doors are closed.
- No keyless entry transmitters are inside the vehicle.
- Rear compartment lid is not ajar.
- Valid hood ajar switch closed signal.
- The doors are locked.
- The hazard switch is OFF.
- Battery reconnect has not occurred.
- Vehicle power mode is correct.

When the IPM determines all conditions meet those required for an RVS event, a message is sent via serial data to the IPM. The ECM relies on the RVS message from IPM, to enable RVS when the crank request signal is received. If the ECM does not receive a valid RVS message, it will not ground the control circuit of the crank relay and start the engine. While the ECM is in RVS mode it will cut fuel to the engine if any of the following additional conditions occur:
- Vehicle speed is greater than 0.
- Transmission is not in P.
- 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.
- Vehicle Theft Deterrent (VTD) tamper.

KEYLESS ENTRY PERSONALIZATION
Vehicle lock/unlock functions and remote vehicle start (RVS) settings may be personalized for 2 separate drivers as part of the remote activation verification feature. For mode descriptions and programming instructions, refer to Vehicle Personalization (w/o Voice Recognition) Vehicle Personalization (w/Voice Recognition) in Personalization.

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 resynchronize when any button on the transmitter is pressed within range of the vehicle. The transmitter will operate normally after the automatic synchronization.