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 2 minutes 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 keyless entry transmitter to unlock the doors.
    • When opening a door or the trunk with the correct key without disarming the CTD system.

The components of the system are:

    • Body Control Module
    • Door Ajar Switches

Important

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

Arming the CTD System

Use the following procedure in order to arm the system:

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

  5. Lock the doors with the LOCK button on the transmitter. The system is in arm pending mode and will not start the arming timer until all doors are closed. The security indicator will remain OFF, until the CTD system is armed. The CTD system will arm after the last door is closed.
  6. The system will arm approximately 30 seconds from the time that the last door is closed. During this delay the THEFT SYSTEM indicator will be OFF. When the indicator transitions to FLASHING, 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 keyless entry transmitter, it must be disarmed.

Important: Using the power door unlock switch or manually unlocking the doors does not disable the CTD armed mode. Also, disconnecting the battery or pulling fuses does not disable the armed mode, since the BCM stores the CTD mode status in memory.

    • To disarm the CTD system in arm pending mode, SECURITY indicator flashing and doors open, perform one of the following:
       - Press the UNLOCK button on the keyless entry transmitter.
       - Insert a valid key into the ignition and start the vehicle.
    • To disarm the CTD system in the armed mode:
       - Press the UNLOCK button on the keyless entry transmitter.
       - Insert a valid key into the ignition and start the vehicle.
    • To disarm the CTD system when activated, alarming mode.
       - Press the UNLOCK button on the keyless entry transmitter.
       - Insert a valid key into the ignition and start the vehicle.

CTD Circuit Description

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

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, it activates the horns and exterior lamps.

When the BCM detects an unauthorized entry, the BCM enters the alarm mode. The BCM activates the horns and exterior lamps for 2 minutes. 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.

Door Ajar Switches

The CTD system uses the door ajar switches in the door jambs as one method to activate the alarm. The body control module (BCM) monitors all door ajar switches via a discrete input from each door ajar switch, including the rear compartment. If the BCM receives a ground signal from a door ajar switch when the CTD system is armed, the BCM activates the alarm.

Inputs

The BCM monitors the following inputs:

    • Driver and passenger door ajar switches
    • Rear compartment ajar switch
    • Transmitter LOCK/UNLOCK buttons, internal function of the BCM
    • Passlockā„¢ Status-the BCM uses the passlockā„¢ status for disarming the system or silencing and alarm when the correct key is used.

Outputs

The BCM controls the following:

    • The horn relay
    • The exterior lights