GM Service Manual Online
For 1990-2009 cars only

The CTD system when armed is designed to deter vehicle content theft by pulsing the horns and exterior lamps for approximately 30 seconds when an unauthorized vehicle entry is detected. However, the CTD system does not affect engine starting.

An unauthorized entry can be any of the following with the CTD system armed:

    • When any door is opened without being unlocked by using the key to unlock either of the front doors or the UNLOCK command from a keyless entry transmitter.
    • Forced entry into the rear compartment.

The components of the system are:

    • Door Lock Actuators
    • Body Control Module (BCM)
    • Remote Control Door Lock Receiver (RCDLR)
    • Door Lock Cylinder Switches
    • Rear Compartment Lid Tamper Switch
    • The security indicator.

Arming the CTD System

Use the following procedure in order to arm the system:

  1. Place the shift lever in Park (P).
  2. Turn OFF the ignition.
  3. Open any door.
  4. Important: The system is not armed if the doors are locked manually, the power door lock switch or remote transmitter must be used to arm the CTD system.

  5. Lock the doors with any power door lock switch or the LOCK button on the transmitter. The system is in standby mode and will not start the arming timer until all doors are closed.
  6. The system will arm within approximately 30 seconds from the time that the last door is closed. This delay is shown by the SECURITY indicator ON STEADY. When the indicator transitions to OFF, the system is armed.

Locking The Vehicle Without Arming The CTD System

Locking the vehicle may be accomplished without arming the CTD system. Use of the manual door locks or using the key to lock the doors will lock the vehicle but will not arm the CTD system.

Disarming an Armed System/Silencing an Alarm

If system arming has been requested by the power door lock switch or the transmitter, it must be disarmed.

Important: Using the power door unlock switch or manually unlocking the doors does not disable the CTD arm mode. Also, disconnecting the battery or pulling fuses does not disable the arm mode.

    • To disarm the CTD system in standby mode, SECURITY indicator on or flashing and any door open:
       - Press either power door unlock switch.
       - Use the key to unlock either front door.
       - Press the UNLOCK button on the transmitter.
    • To disarm the CTD system in the armed mode:
       - Use the key to unlock either front door.
       - Press the UNLOCK button on the transmitter.
    • To disarm the CTD system when in the alarming mode.
       - Use the key to unlock either front door.
       - Press the UNLOCK button on the transmitter.

Personalization

Refer to Personalization Description and Operation in Personalization.

CTD Circuit Description

The following is a description of each component used in the CTD system:

Door Lock Actuators

The CTD system uses the door open switches in the door lock actuators as one method to activate the alarm. The body control module (BCM) monitors all door open switches via a discrete input. The alarm mode activates when both of the following conditions are met:

    • The BCM detects any door is open.
    • The CTD system is in the armed mode.

Body Control Module (BCM)

The CTD system is an internal function of the body control module (BCM) which utilizes class 2 serial data and various switch input information to perform CTD functions. When the BCM detects an unauthorized entry, the BCM applies ground to activate the horns and exterior lamps. The BCM has five basic modes:, disarmed, standby, delayed, armed, and alarm for operating the CTD system. The different modes are described below.

  1. The BCM has the CTD system in a disarmed mode until the following conditions are detected:
  2. • Ignition key turned to the OFF position
    • Any door open
    • Doors locked by either the power door lock switch or the LOCK button on the transmitter
  3. The BCM enters the standby mode when the above conditions are detected. In standby mode the BCM commands the instrument cluster to illuminate the SECURITY indicator via the class 2 serial data circuit. If all the doors are closed and the LOCK button on the transmitter is used, the BCM enters the delayed mode.
  4. When the last door is closed, the BCM enters the delayed mode for 30 seconds. In delayed mode the BCM commands the instrument cluster to illuminate the SECURITY indicator on steady via the class 2 serial data circuit.
  5. After 30 seconds, the BCM enters the armed mode. In armed mode the BCM commands the instrument cluster to turn off the SECURITY indicator via the class 2 serial data circuit. Any forced entry activates the alarm mode.
  6. When the BCM detects a forced entry, the BCM enters the alarm mode. The BCM applies ground to activate the horn and exterior lamps for 30 seconds, via a class 2 message. This is followed by a three minute time-out with the horn no longer active. If no new intrusions are detected after the time-out, the horn is not active. The system must be disarmed or the intrusion condition removed after the time-out for the system to exit alarm mode.

Remote Control Door Lock Receiver (RCDLR)

The keyless entry system may also arm and disarm the CTD system. When the RCDLR receives a door lock/unlock signal from the transmitter, the RCDLR sends a class 2 message to the BCM to perform the appropriate door lock/unlock command. The BCM performs one of the following functions:

  1. Locks the doors and enters the armed mode.
  2. Unlocks the doors and enters the standby mode.

Door Lock Cylinder Switches

The front door lock cylinders are equipped with switches in order to disarm the CTD system. When the lock cylinder is turned to the unlock position the switch grounds the key switch signal input to the BCM .

Rear Compartment Lid Tamper Switch

The rear compartment lid lock cylinder is equipped with a tamper switch. Any forced movement of the lock cylinder activates the tamper switch. Both or either of the following actions activate the lock cylinder tamper switch:

    • Rotation caused by forced entry.
    • In and out movement of the lock cylinder caused by forced entry.

Security Indicator

The content theft deterrent (CTD) system uses the security indicator as a status indicator. The body control module (BCM) commands the instrument panel cluster (IPC) to illuminated the security indicator on steady or to flash the security indicator only when the ignition switch is in the off position via the class 2 serial data circuit. The security indicator will be requested to flash or to be illuminated on steady under the following conditions:

    • The BCM will command the IPC to flash the security indicator when either front door is open.
    • The BCM will command the IPC to illuminated the security indicator on steady when either front door is open and the doors are locked by the power door lock switch or a lock command from the keyless entry system.

Important

The CTD system can be armed with the windows or sunroof open.

Inputs

The Body Control Module (BCM) monitors the following inputs:

    • Door open switches.
    • Driver and passenger power door lock/unlock switches.
    • Front door lock cylinder switches.
    • Rear compartment lid tamper switch.
    • Transmitter LOCK/UNLOCK buttons, class 2 message from the remote control door lock receiver (RCDLR).

Outputs

The Body Control Module (BCM) commands the following:

    • The horn relay
    • The headlamp relay
    • The park lamp relay