For 1990-2009 cars

## Keyless Entry System Description and Operation with ATG

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/liftgate, operate the power liftgate (if equipped), or release the liftglass when a corresponding button on the keyless entry transmitter is pressed. This is accomplished by the transmitter sending a radio frequency to the BCM. The BCM interprets the signal and performs the requested function. A low transmitter or vehicle 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 may also cause interference that could lead to a malfunction. Keyless entry allows you to operate the following components:

• | Door locks

• | Liftgate lock

• | Power liftgate, if equipped

• | Liftglass, if equipped

• | Remote vehicle starting, if equipped

• | Illuminated entry lamps

• | Vehicle locator/Panic alarm

• | Comfort Open and Comfort Close, if equipped

The keyless entry system has the following components:

• | Keyless entry transmitters

• | BCM

### Keyless Entry Transmitters

The keyless entry transmitters are used to lock and unlock the vehicle door while away from the immediate are of the vehicle. Vehicles without remote vehicle start will operate at a distance of up to 20 m (65 ft) away, except for Japanese and South Korean vehicles, which are limited to 4 m (16 feet). Vehicles with remote vehicle start will operate at a distance of up to 60 m (195 ft) away. Up to 8 transmitters may be programmed to a single vehicle.

### Body Control Module (BCM)

The BCM is a multifunction module that operates the keyless entry system. When an radio frequency message is received from a keyless entry transmitter, the BCM interprets this signal and performs the specific function, i.e. door lock, door unlock, or vehicle locate.

### Unlock Driver Door Only

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 enabled through personalization.

• | Disarm the content theft deterrent (CTD) system, if equipped.

• | Deactivate the CTD system when in the alarm mode.

### Unlock All Doors - Second Operation

Momentarily press the transmitter UNLOCK button a second time, within 5 seconds of the first press, to perform the following functions:

• | Unlock the remaining doors.

• | Unlock the liftgate, if equipped.

### 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.

• | Chirp the horn, if enabled through personalization.

• | Arm the CTD system, if equipped.

### Liftglass Release, if equipped

Press the transmitter liftglass release button to perform the following function:

Open the liftglass.

### Power Liftgate, if equipped

Press and hold the power liftgate button to perform the following functions:

• | Open or close the liftgate using the power liftgate function.

• | Flash the tail lamps.

• | Sound the interior power liftgate chime.

### Vehicle Locator/Panic Alarm

A single press of the panic button performs the following functions. Some functions may be dependent on personalization settings:

• | Pulse the horn 3 times.

• | Flash the exterior lamps 3 times.

A press and hold of the panic button performs the following functions:

• | Illuminate the interior lamps.

• | Pulse the horn and flash the exterior lamps for 30 seconds or until the following conditions occur:

- | The panic button is pressed.

- | The ignition switch is turned to the RUN position with a valid key.

### Comfort Open and Comfort Closed, if equipped

Holding down the appropriate button on the transmitter will perform the following functions:

• | Open all vehicle windows

• | Close all vehicle windows

### Remote Vehicle Start, if equipped

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. Remote Vehicle Start functions have an operating range of up to 195 feet, depending on conditions. The remote vehicle start sequence begins by pressing and releasing the lock button and then pressing and holding the remote vehicle start 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 remote vehicle start 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 remote vehicle start time may be extended by an additional 10 minutes by again pressing and releasing the lock button and then pressing and holding the remote vehicle start buttons on the transmitter. This feature is called a remote vehicle start continue and allows a maximum of 20 minutes of engine running. If the remote vehicle start continue is performed at 7 minutes into the initial 10 minute time-out, a total of 17 minutes of engine running would occur. The remote vehicle start event may be suspended 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.

In between ignition cycles, only 2 remote vehicle start events may occur or be attempted. Once 2 events or attempts have been made, future remote vehicle start events will be suspended until the vehicle is started using the ignition.

### Enable/Disable Remote Vehicle Start

Using the driver information center, remote vehicle start 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 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

The BCM receives a signal from the keyless entry transmitter indicating a remote vehicle start 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 remote vehicle start 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 remote vehicle start event, a message is sent via serial data to the ECM. The ECM relies on the remote vehicle start message from BCM to enable remote vehicle start when the crank request signal is received. If the ECM does not receive a valid remote vehicle start message, it will not attempt to start the engine. While the ECM is in remote vehicle start 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 remote vehicle start settings may be personalized. For functional descriptions and personalization instructions, refer to the vehicle owners manual.

## Keyless Entry System Description and Operation with ATS

### 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 Body Control Module (BCM). The BCM interprets the signal and activates the requested 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

#### 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. 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 4 different areas on the vehicle to determine the location of the transmitter. When passively opening a locked door or the rear compartment lid, you must have a programmed transmitter with you in your pocket, purse, or briefcase. As a customer opens the door handle or presses the rear compartment touch 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 in order to receive the challenge. If the challenge is met, the transmitter will respond, allowing the door to be unlocked and opened. Passive entry allows you to operate the following features:

• | Passive door unlock/unlatch

• | Passive rear compartment lid release

• | Illuminated entry lamps

• | Vehicle starting

The keyless entry system has the following components:

• | Keyless entry transmitters

• | Left hand and right hand door antennas (part of the door handle assembly)

• | Rear compartment antenna

• | Console passive antenna

• | Console active antenna

• | Interior trunk antenna

• | Body Control Module (BCM)

• | Keyless Entry Control Module

### Keyless Entry Transmitters

The keyless entry transmitters are used to passively or actively lock and unlock the vehicle doors.

By operating any of the exterior door handles, a nearby programmed transmitter is challenged by a keyless entry antenna. The transmitter will passively send a radio frequency signal to the Keyless Entry Control Module via the door antennas; the request is then sent to the BCM. The BCM will interpret this communication and either allow entry into the vehicle or deny it.

### Door Antennas

The keyless entry door antennas are used to transmit low frequency communications to the keyless entry transmitters.

The keyless entry door antennas are molded into the vehicles left front and right front exterior door handles. The antennas are serviced as part of the door handle assembly. The antennas are controlled by the Keyless Entry Control Module. 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.

### Rear Compartment Antenna

The rear compartment antenna is used to transmit low frequency communication to the keyless entry transmitters for entry to rear compartment.

The rear compartment antenna is located under the rear fascia and is accessed from under the vehicle. The antenna is controlled by the Keyless Entry 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.

### Console Passive Antenna

The keyless entry console passive antenna is used for both keyless entry and vehicle starting functions. In their keyless entry function, they are used to locate any keyless entry transmitters within the vehicle. In the antenna's vehicle starting function, the antenna transmit and receive the needed communications with the keyless entry transmitter to enable vehicle starting.

### 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 signal is being interrupted.

The purpose of the console active antenna is to send a low frequency radio frequency challenge to a programmed key fob when the start button is pressed. The console active antenna is controlled by the Keyless Entry Control Module.

### Keyless Entry Control Module

The Keyless Entry Control Module is a multi-function module which controls all the vehicles antennas for passive keyless entry functions.

### Body Control Module (BCM)

The Body Control Module (BCM) is a multi-function module that performs the following functions:

• | Receive active signals from fobs

• | Authenticate the active signal

• | Determine the functionality requested by the fob signal

• | Perform the function requested by the fob signal

### 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 enable 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 pull the door handle to perform the following functions:

• | Unlock only the driver door when door handle is operated

• | Disarm the CTD system, if equipped

• | Deactivate the CTD system when in the alarm mode

### Unlock All Doors - Passive

If enabled through personalization, approach any door (front or rear) with a valid keyless entry transmitter to perform the following functions:

• | Unlock all vehicle doors when the approached door handle is operated

• | 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

If enabled through personalization, exit the vehicle with the keyless entry transmitter to perform the following functions:

• | 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

The doors can also be locked from the exterior by pressing the touchpad on the outside of a door handle with a valid transmitter in range.

If more than one keyless entry transmitter is within a vehicle and the Keyless Entry Control Module detects that transmitter has been left in the vehicle after an exit, the transmitter left within the vehicle will be temporarily deactivated until the CTD system has been disarmed.

### 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. Press the rear compartment lid release touch pad. The rear compartment lid will open.

A 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.

### Vehicle Locator/Panic Alarm

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:

• | Illuminates the interior lamps

• | 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

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. Remote vehicle start functions have an operating range of up to 195 feet, depending on conditions. The remote vehicle start sequence begins by pressing and releasing the lock button and then pressing and holding the remote vehicle start buttons on the keyless entry transmitter. 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 or vehicle key at any time. Once activated, the engine is allowed to run for 10 minutes. The remote vehicle start time may be extended by an additional 10 minute by again pressing and releasing the lock button and then pressing and holding the remote vehicle start buttons on the transmitter. This feature is called a remote vehicle start continue and allows a maximum of 20 minutes of engine running. If the remote vehicle start continue is performed at 7 minutes into the initial 10 minute time-out, a total of 17 minutes of engine running would occur. The remote vehicle start event may be suspended 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.

In between ignition cycles, only two remote vehicle start events may occur or be attempted. Once two events or attempts have been made, future remote vehicle start events will be suspended until the vehicle is started using the ignition.

### Enable/Disable Remote Vehicle Start

Using the driver information center, remote vehicle start 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 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

The Keyless Entry Control Module receives a signal from the keyless entry transmitter indicating a remote vehicle start request. A message is then sent to the BCM which determines if a crank request message will be sent to the ECM to activate remote vehicle start. The BCM looks at the following inputs to verify the system is ready for an remote vehicle start event:

• | Vehicle is not in valet mode

• | All vehicle doors are closed

• | Rear compartment lid is not ajar

• | The hood is closed

• | The doors are locked

• | The hazard switch is OFF

• | Battery reconnect has not occurred

• | Vehicle power mode is correct.

When the BCM determines all conditions meet those required for an remote vehicle start event, a message is sent via serial data to the BCM. The ECM relies on the remote vehicle start message from BCM, to enable remote vehicle start when the crank request signal is received. If the ECM does not receive a valid remote vehicle start message, it will not ground the control circuit of the crank relay and start the engine. While the ECM is in remote vehicle start 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.

• | Immobilizer system indicates a theft attempt

### Keyless Entry Personalization

Vehicle lock/unlock functions and remote vehicle start settings may be personalized for the vehicle. For functional descriptions and programming instructions, refer to the vehicle owners manual.

### Low Fob Battery Message

A LOW FOB BATTERY message may be seen on the driver information center when the fob’s battery voltage has been lower than 2.6 volts for three consecutive ignition cycles (OFF to ACC or OFF to RUN). The Keyless Entry Control Module monitors the voltage of each fob independently; however, if two fobs are present when starting the vehicle, the voltage will be monitored only on the fob that starts the vehicle. For example, if Fob 1 enters from the driver door and Fob 2 enters from the passenger door, the Keyless Entry Control Module will monitor only Fob 1. To determine the fob being monitored, check which driver ID is present when the vehicle is started. The driver ID will correspond with the fob being monitored.

Fob battery voltage may also be observed using the scan tool. The scan tool displays the actual battery signal voltage, as well as the low voltage signal. These parameters may be used to determine which fob has caused the LOW FOB BATTERY message to be displayed.