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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Blazer - 2WD 🢒 Body and Accessories 🢒 Theft Deterrent 🢒 Content Theft Deterrent (CTD) Description and Operation

Content Theft Deterrent (CTD) System

The Content Theft Deterrent function provides the theft deterrent by sounding the horn and flashing the headlamps and the park lamps when there is an unauthorized vehicle entry or there is tampering detected.

SECURITY Telltale

The SECURITY telltale on the instrument cluster is controlled by both the VTD system and the CTD system.

    • The VTD system commands the instrument cluster to control the telltale only when the ignition switch is ON. The VTD system uses the telltale as a malfunction indicator. If a DTC is present in the VTD system when the ignition is ON, the telltale will be illuminated.
    • The CTD system commands the instrument cluster to control the telltale only when the ignition switch is OFF. The CTD system uses the telltale to identify system status.
       - Telltale FLASHING -- The system is in standby mode. The system is not ready to arm, a door is open.
       - Telltale ON STEADY -- The system is in delay mode. The system is ready to arm and is executing a time delay of 15 seconds before turning the lamp OFF and transitioning to armed mode.
       - Telltale OFF -- The system may or may not be armed.

Body Control Module (BCM)

The body control module (BCM) monitors several inputs in order to arm and disarm the CTD system. The BCM controls the alarm function outputs. When the BCM detects an unauthorized entry, any door opened, the BCM applies ground to the horn, the park lamp and the headlamp relays. The BCM will send messages to the security telltale in the instrument cluster through the Class 2 serial data link. The BCM has the following 8 basic modes for operating the CTD system. The more detailed descriptions are below.

    • Off state
    • Idle state
    • Disarmed state
    • Ready-to-arm state
    • Arm initiated state
    • Arm delay state
    • Armed state
    • Alarm state

The BCM has the following 6 discrete inputs in order to monitor the CTD system:

    • Ignition 1
    • Driver door latch, door jamb switch
    • Passenger door latch, door jamb switch
    • Door lock relay
    • Door key switch
    • Passenger door unlock relay

The BCM applies ground once per second for approximately 2 minutes, or until a valid input to disarm the system is received by the BCM.

Door Latch, Door Jamb Switches

The theft deterrent system uses the door latch switch as one method in order to activate the alarm. If the BCM detects any door opening before the BCM receives a disarm input, the alarm mode activates.

Door Key Switch

The BCM monitors the door key switches in order to disarm the CTD system. When the lock cylinder turns in order to unlock the door, the switch grounds the disarm input to the BCM.

Remote Control Door Lock Receiver Module System

The remote control door lock receiver module system may also arm and disarm the CTD system. When the remote control door lock receiver receives a door lock or an unlock signal from the key fob, the remote control door lock receiver sends a message to the BCM. The message orders the BCM to perform the appropriate door lock/unlock command. The BCM detects the message and performs one of the following functions:

    • Locks the doors and enters the armed initiated mode
    • Unlocks the doors and enters the ready-to-arm mode

Off State

The CTD system will be in the off state when the ignition switch is in the RUN position and all the doors are closed. The BCM will request the security telltale to remain OFF.

Idle State

The CTD system will be in the idle state when the ignition switch is in the RUN position and any door is open. The BCM will request the security telltale to remain OFF.

Disarmed State

The CTD system will be in the disarmed state when the ignition switch is in the LOCK off position and all the doors are closed. The BCM will request the security telltale to remain OFF.

Ready-To-Arm State

The CTD system will be in the ready-to-arm state when the ignition switch is in the LOCK off position and any door opens. The BCM will request the security telltale to flash.

Arm Initiated State

The CTD system will be in the arm initiated state when the ignition switch is in the LOCK off position, any door opens, and the BCM detects a lock command from either the power door lock switch or the remote control door lock receiver. The BCM will request the security telltale to remain ON.

Arm Delay State

The CTD system will enter the arm delay state when the ignition switch is in the LOCK off position, the BCM receives a LOCK command from either the power door lock switch or the remote control door lock receiver and all the doors are closed. The BCM will request the security telltale to remain ON for 15 seconds.

Armed State

The CTD system will enter the armed state after the 15 second delay of the arm delay state, unless the BCM detects any door opening within that time. The BCM monitors the inputs, listed above, in order to determine whether to activate the alarm or to disarm the system. The BCM will request the security telltale to remain OFF.

Alarmed State

The CTD system will enter the alarmed state from the armed state if any door opens. The horns and the exterior lights will alternate off and on for approximately two minutes or until an unlock command is received by the BCM. If the BCM does not receive an unlock command, the CTD system will go back to the armed state. The BCM will request the security telltale to remain off. The CTD system will change from the alarm state to the off state if the vehicle control module (VCM)/powertrain control module (PCM) receives a valid Passlock™ ignition key rotation.

Remote Panic Alarm/Vehicle Locator State

The CTD system will enter the remote panic alarm/vehicle locator state when the panic button on the key fob is pressed. When the panic button is pressed, the remote control door lock receiver sends a message to the BCM. The BCM will sound the horns and flash the headlamps and the park lamps. You can disable the remote panic alarm/vehicle locator state by pressing the panic button on the key fob again or the system will time out after 30 seconds.

Locking the Vehicle Without Arming the System

Use one of the following procedures in order to lock the vehicle without arming the system:

    • Procedure A -- Lock the vehicle using the manual door lock knobs. Close all the doors.
    • Procedure B -- Close all the doors. Use the key or the power door lock switch in order to lock the door. The doors must be closed prior to locking the doors for this procedure.

Disarming the System

In the arm initiated mode, the following conditions are true:

    • The security telltale is ON.
    • The doors are open.

In order to disarm a system in the arm initiated mode, perform one of the following procedures:

    • Press the power door lock switch to the UNLOCK position.
    • Press the door unlock button on the key fob.

In order to disarm a system in the arm delay or the armed mode, perform one of the following procedures:

    • Use the key in order to unlock one of the doors.
    • Press the door unlock button on the key fob.

Deactivating the Alarm

In the alarm mode, the following conditions are true:

    • The horns sound intermittently.
    • The headlights and the park lamps are flashing.

In order to deactivate a system in the alarm mode, perform one of the following procedures:

    • Use the key in order to unlock one of the doors.
    • Press the door unlock button on the key fob.
    • If the vehicle control module (VCM)/powertrain control module (PCM) receives a valid Passlock™ ignition key rotation.

Alarm State Activation

Perform the following steps in order to verify that the system activates the alarm state:

  1. Open a window. Opening the window ensures that you will be able to open the door from the outside using the manual door lock knob.
  2. Place the system in the armed state.
  3. Reach through the window and unlock the door using the manual door lock knob.
  4. Open the door.

The system enters the alarm state. The following actions occur for approximately 2 minutes:

    • The horns sound intermittently.
    • The exterior lamps flash.
    • After 2 minutes and all the doors closed, the system automatically returns back to the armed state.

Return System to Arm Initiated State

Perform the following steps in order to verify that the system returns to the armed initiated mode:

  1. Place the system in the armed mode.
  2. Use the key in order to unlock the door.
  3. Open the door.
  4. The system does not enter the alarm mode. The SECURITY telltale flashes. The flashing telltale indicates that the system has entered the ready-to-arm state.
  5. Press the power door lock switch to the LOCK position or the key fob LOCK button.

Ignition Switch Disarm Function

Perform the following steps in order to verify that the ignition disarm function operates:

  1. Stay in the vehicle.
  2. Place the system in the armed state.
  3. Wait for the SECURITY telltale to turn off. The system is armed when the SECURITY telltale turns off.
  4. Cycle the ignition switch from the LOCK position to the RUN position. Return the ignition switch to the LOCK position.
  5. Open any door.

The system does not enter the alarm mode. The SECURITY telltale flashes. The flashing telltale indicates that the system has entered the ready-to-arm state.