GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2005 🢒 GMC C Sierra - 2WD 🢒 Accessories 🢒 Theft Deterrent 🢒 Keyless Entry System Description and Operation

The keyless entry system is a supplementary vehicle entry device. Radio frequencies or discharged batteries may disable the system.

Keyless entry can operate the following components:

    • The door locks
    • The interior lamps
    • The parking lamps
    • The headlamps
    • The puddle lamps (if equipped)
    • The horn

The keyless entry system has the following main components:

    • The transmitters
    • The passenger door module (PDM)

The PDM communicates with the body control module (BCM) through the keyless entry serial data circuit. When you press a button on a transmitter, the transmitter sends a signal to the PDM. The PDM sends a request to the BCM and the BCM performs the appropriate function.

Unlock Button

Press the UNLOCK button once in order to perform the following functions:

    • Unlock the driver door only.
    • Illuminate interior lamps for a predetermined amount of time or until the ignition is turned to the RUN position with a valid key.
    • Illuminate the puddle lamps (if equipped) for a predetermined amount of time or until the ignition switch is turned to the RUN position with a valid key.
    • Disarm the content theft deterrent (CTD) system (if equipped).
    • Deactivate the CTD system when in the Alarm Mode (if equipped).

Unlock All Doors (Second Operation)

Press the UNLOCK button a second time within 3 seconds of the first press in order to perform the following functions:

    • Unlock all doors.
    • Flash the parking lamps twice.

Lock All Doors

Pressing the lock button will:

    • Lock all of the doors.
    • Turn the interior lamps on for 2 seconds.
    • Turn the puddle lamps on (if equipped) for 2 seconds.
    • Arm the content theft deterrent (CTD) system (if equipped).

Press the LOCK button again within 3 seconds of the first press in order to perform the following functions:

    • Chirp the horn.
    • Turn the interior lamps on for 2 seconds.
    • Turn the puddle lamps on (if equipped) for 2 seconds.

Panic Alarm

Important: On some export vehicles the panic alarm will not reset after a predetermined amount of time. The panic alarm must be manually turned OFF using one of the methods listed below.

A single press of the transmitter panic button will:

    • Pulses the horn.
    • Illuminates the interior lamps.
    • Flash the parking lamps.
    • Flash the headlamps .
    • Turn the puddle lamps on (if equipped).

All of the above will occur for a predetermined amount of time or until:

    • The Panic button on the transmitter is pressed again.
    • The vehicle is unlocked with the key.
    • The ignition switch is turned to the RUN position with a valid key

Keyless Entry Personalization

Personalization of the remote activation verification is only available on select vehicles equipped with either a Driver Information Center or a Secondary Information Center. For mode descriptions and programming instructions, refer to Driver Personalization 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 PDM are synchronized to the appropriate order. If a programmed transmitter sends a signal that is not in the order that the PDM 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.