GM Service Manual Online
For 1990-2009 cars only

Keyless Entry System Description and Operation - Active

The keyless entry system is a vehicle entry device. Use the keyless entry system in conjunction with the door locks to unlock a vehicle. The keyless entry will unlock/unlatch the vehicle doors or open the rear compartment lid when a corresponding button on the key fob is pressed. This is accomplished by the key fob sending a radio frequency to the remote control door lock receiver (RCDLR). The signal is received by the RCDLR via an internal antenna located within the RCDLR. Japan export vehicles are equipped with an external antenna. The RCDLR interprets the signal and activates the requested function via a class 2 message over the serial data line. A low transmitter battery or radio frequency (RF) interference from aftermarket devices such as 2-way radios, power inverters, cellular phone chargers, computers, etc. may cause a system malfunction. High RF traffic areas, such as gas stations which 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 active keyless entry system has the following components:

    • The #1-#4 keyless entry transmitters
    • The remote control door lock receiver (RCDLR)
    • External antenna (Japan export only)

Keyless Entry System Description and Operation - Passive

The passive keyless entry allows you to enter a locked vehicle without pressing any button on the key fob transmitter. You must only have the fob 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 fob 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 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/briefcase. As a customer presses an exterior door handle switch or exterior rear compartment lid release switch, the low frequency antenna sends out a challenge to the key fob. The key fob 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 key fob will respond to the remote control door lock receiver (RCDLR) via a radio frequency signal 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 key fob and if the challenge is met, the fob will respond to the 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, cellular phone chargers, computers, etc. may cause a system malfunction. High RF traffic areas, such as gas stations which 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 transmitters, up to 4 total
    • The RCDLR
    • The keyless entry antenna - left, located in the lower B-pillar area at door height
    • The keyless entry antenna - Right, located in the lower B-pillar area at door height
    • The keyless entry antenna - rear, located in the rear compartment area near the rear compartment lid latch
    • The keyless entry antenna - back up, located inside the passenger compartment inside the glove box area

Keyless Entry Transmitters

The keyless entry transmitters are used to passively or actively lock and unlock the vehicle. When any one of the 4 allowable programmed key fobs are challenged by a keyless entry antenna by depressing either of the exterior door open switches, the transmitters will passively send an 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. The vehicle comes with two transmitters. Each transmitter will have a number on top of it, "1" or "2"; these numbers correspond to a separate driver of the vehicle.

Keyless Entry Antennas

The keyless entry antennas are used to transmit and receive RF communication with the keyless entry transmitters when accessing the vehicles doors or rear compartment.

The antennas are controlled by the remote control door lock receiver (RCDLR). When an exterior door handle switch or exterior rear compartment lid release switch is pressed, the respective antenna sends out a challenge to the transmitter, which begins the passive entry communications.

The keyless entry antenna backup is located in the glove box area. 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 jammed.

The purpose of the keyless entry antenna backup is to send a low frequency RF challenge to a programmed key fob, inside the interior of the vehicle, when the start button is pressed. The keyless entry antenna backup is controlled by the RCDLR.

Remote Control Door Lock Receiver (RCDLR)

Important: The remote control door lock receiver (RCDLR) is not on the GM LAN high speed bus, therefore the RCDLR and the engine control module (ECM) must use the body control module (BCM) as a gateway in order to communicate.

The RCDLR is a multi-function module located in the center of the dash panel. The keyless entry antennas are controlled by the RCDLR to allow passive vehicle entry, as well as vehicle starting and vehicle theft deterrent operations. The RCDLR will send an AC voltage signal and provide ground to the keyless entry antenna when an exterior door handle switch, exterior rear compartment lid release, or the Start/Acc/Off switch is depressed. This will enable the keyless entry antenna to send out a low frequency broadcast challenge to a key fob in range. The RCDLR also has an internal radio frequency (RF) antenna to receive the key fobs passively or actively sent signal.

Starting the Vehicle/ACC mode

To start a vehicle you must have a valid key fob 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, cellular phone chargers, computers, etc. High RF traffic areas, such as gas stations which 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 glove box for the key fob to slide into. The key fob must be inserted into the pocket bottom edge first with the buttons facing towards the passenger side of the vehicle. With the key fob inserted into the pocket correctly, a low frequency coupling will occur between the key fob and the antenna when the Start mode or ACC/OFF mode button is pressed. This procedure will put the vehicle in limp home mode and allow the vehicle to be operated.

Ignition 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 key fob within the passenger compartment of the vehicle, the brake pedal depressed, and the transmission in Park or Neutral. Once that criteria is met, the customer must press and hold for 5 seconds the ACC/OFF portion of the Start/ACC/OFF mode button. 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, cellular phone chargers, computers, etc. may cause a system malfunction. High RF traffic areas, such as gas stations which 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 key fob 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. 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, cellular phone chargers, computers, etc. High RF traffic areas, such as gas stations which use pay-at-the-pump RF transponders, may also cause interference. For a vehicle to transition to the OFF mode, automatic transmissions must be placed in Park and manual transmissions must be placed in Reverse. If the transmission is not in Park (automatic transmissions) or Reverse (manual transmissions) when the OFF button is pressed, the engine will shut off, but the vehicle will remain the ACC mode. Should this occur, vehicles equipped with an automatic transmission will automatically switch to the OFF mode after approximately 10 minutes. Vehicles equipped with a manual transmission, however, will not transfer out of the ACC mode. Manual transmission vehicles will remain in the ACC mode which will cause a parasitic battery draw. Vehicles left in this ACC mode state are considered to still have the fob in the vehicle and may be started without a fob should the operator exit the vehicle.

While in normal RUN mode if the key fob 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 with out 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 three times alerting the customer the key fob has been left in the vehicle. This feature can be turned On/Off through DIC personalization.

Unlock Driver Door Only - Active

Momentarily press the key fob UNLOCK button in order to perform the following functions:

    • Unlock only the driver door.
    • Illuminate the interior lamps for approximately 40 seconds, 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 key fob UNLOCK button a second time, within 4 seconds of the first press, to perform the following functions:

    • Unlock the remaining doors.
    • Illuminate the interior lamps for approximately 40 seconds, or until the ignition is turned ON.
    • Flash the exterior lights, if selected ON in personalization.
    • Chirp the horn.

Unlock Driver Door Only - Passive

Approach the drivers door with a valid key fob to perform the following functions:

    • Unlock only the driver door when the driver door handle pad is pressed.
    • Disarm the content theft deterrent (CTD) system, if equipped.
    • Deactivate the CTD system when in the alarm mode.

Unlock All Doors - Passive

Approach the drivers door with a valid key fob to perform the following functions:

    • Unlock the driver and passenger door when the driver side door handle is pressed; this feature may be turned On/Off through personalization.
    • Disarm the content theft deterrent (CTD) system, if equipped.
    • Deactivate the CTD system when in the alarm mode.

or

Approach the passenger door with a valid key fob to perform the following functions:

    • Unlock the passenger and driver door when the passenger side door handle is pressed.
    • Disarm the content theft deterrent (CTD) system, if equipped.
    • Deactivate the CTD system when in the alarm mode.

Lock All Doors - Active

Press the key fob 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.
    • Arm the content theft deterrent (CTD) system.

Lock All Doors - Passive

With passive locking enabled in the DIC personalization, exit the vehicle with the key fob to perform the following functions:

    • Lock all vehicle doors, if selected On in personalization.
    • Chirp horn, is selected ON in personalization.
    • Arm the content theft deterrent (CTD) system.

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 key fob rear compartment release button will open the rear compartment lid.

Rear Compartment Lid Release - Passive

Approach the rear of the vehicle with a valid key fob, push the rear compartment open pad the rear compartment lid will open.

Keyless Entry Personalization

The following items may be personalized through the DIC for Driver 1 or Driver 2:

    • Flash at unlock, Yes/No
    • Flash at lock, Yes/No
    • Fob reminder, On/Off
    • Passive door locking, Off/Silent/Horn
    • Passive door unlock, Driver/Both

Key fobs programmed for Driver 1 and Driver 2 can be programmed to recall personalization features. When the vehicle is accessed with the 3rd or 4th programmed fob, OPTIONS NOT AVAILABLE is displayed on the DIC. With the 3rd or 4th programmed fobs, personalization settings can be changed only for the ignition cycle. None of the personalization settings selected or changed can be recalled with the 3rd or 4th programmed key fob. Accessing the vehicle with any key fobs not programmed for Driver 1 or Driver 2 causes the OPTIONS NOT AVAILABLE message to display on the DIC. For more information on programming instructions and personalization, refer to the Owners Manual.

Low Fob Battery Message

A LOW FOB BATTERY message may be seen on the DIC 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 RCDLR 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 RCDLR 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.