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:

    • Forced entry into the passenger compartment.
    • 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:

    • Remote Control Door Lock Receiver (RCDLR)
    • Door Jamb Switches
    • Body Control Module
    • Front Door Lock Cylinder Switches
    • Liftgate Key Cylinder Unlock Switch, if equipped
    • Lift Glass Ajar Switches, if equipped
    • Power Door Lock Switches

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 power door lock switch or remote keyless entry transmitter must be used to arm the CTD system.

  5. Lock the doors with the 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 approximately 30 seconds from the time that the last door is closed. This delay is shown by the theft LED indicator ON STEADY. When the indicator transitions to flashing slowly 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 keyless entry 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, since the BCM stores the CTD mode status in memory.

    • To disarm the CTD system in standby mode (theft LED flashing fast and door(s) open), perform one of the following:
       - Press either power door unlock switch.
       - Use the key to unlock either front door.
       - Press the UNLOCK button on the keyless entry transmitter.
       - Insert a valid key into the ignition and switch to the ON position.
    • To disarm the CTD system in the armed mode:
       - Use the key to unlock the either front door.
       - Press the UNLOCK button on the keyless entry transmitter.
       - Insert a valid key into the ignition and switch to the ON position
    • To disarm the CTD system when activated (alarming mode).
       - Use the key to unlock either front door.
       - Press the UNLOCK button on the keyless entry transmitter.
       - Insert a valid key into the ignition and switch to the ON position.

CTD Circuit Description

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

Remote Control Door Lock Receiver (RCDLR)

The keyless entry system can arm and disarm the CTD system. When the keyless entry module receives a door lock or unlock signal from the transmitter, the keyless entry module sends a message to the BCM on the keyless entry serial data link to perform the appropriate arm/disarm functions.

Door Jamb Switches

The front door lock cylinder switches are internally integrated within the door lock assemblies. The body control module (BCM) monitors all door jamb switches via a discrete input from each door jamb switch, including the rear door(s). If the BCM receives a ground signal from a door jamb switch when the CTD system is armed, the BCM activates the alarm.

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. 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 theft LED to flash quickly. 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 theft LED to illuminate ON steady.
  5. After 30 seconds, the BCM enters the armed mode. In armed mode, the BCM commands the theft LED to flash slowly. Any forced entry activates the alarm mode.
  6. When the BCM detects a forced entry, the BCM enters the alarm mode. The BCM activates the horns and exterior lamps for 30 seconds. 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.
  7. There is an arm simulate mode that occures when the LED will flash continously after 60 seconds when a the last door is closed without an arming CTD request.

Front Door Lock Cylinder Switches

The front door lock cylinder switches are internally integrated within the door lock assemblies. The front door lock cylinder switches use a discrete input to the BCM. The BCM utilizes each of these inputs to disarm the CTD system. Inserting a key and turning to the unlock position will disarm the CTD system.

Liftgate Key Cylinder Unlock Switch

If equipped, the liftgate key cylinder unlock switch uses a discrete input to the BCM. The BCM utilizes this input to enable access into the rear compartment area without causing the alarm to sound. The CTD system remains armed until one of the disarm procedures are performed.

Lift Glass Ajar Switches

If equipped, the lift glass ajar switches use a descrete input to the BCM. The BCM utilizes these inputs from each lift glass ajar switch. If the BCM receives a ground signal from a lift glass ajar switch when the CTD system is armed, the BCM activates the alarm.

Power Door Lock Switches

The power door lock switches are used to either arm or disarm the CTD system. Pressing the lock position will cause the CTD to arm after all doors are closed and the 30 second delay period has elapsed. Pressing the unlock position when the CTD system is in the standby mode will disarm the system. When the CTD system has entered into the armed mode the power door lock switches are inactive and cannot unlock the doors or disarm the CTD system.

Important

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

Inputs

The BCM monitors the following inputs:

    • Driver and passenger door jamb switches.
    • Driver and passenger power door lock/unlock switches.
    • Front door lock cylinder disarmswitches.
    • Liftgate key cylinder unlock switch, if equipped.
    • Transmitter LOCK/UNLOCK buttons, class 2 message from the Remote Keyless Entry (RKE) Module.

Outputs

The BCM controls the following :

    • The horn relay
    • The exterior lights