CTD Circuit Description

WARNING: This page is about a different car, the 2011 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

The following is a description of each component used in the content theft deterrent (CTD) system:

Body Control Module (BCM)

The CTD system is an internal function of the BCM which utilizes serial data and various switch inputs information to perform CTD functions. When the BCM detects an unauthorized entry, it activates the horns and exterior lamps. The BCM has 4 basic modes (disarmed, standby, armed, and alarm) for operating the CTD system. The different modes are described below.

The BCM has the CTD system in a disarmed mode until the following conditions are detected:
- Ignition key turned to the OFF position.
- Doors locked by either the power door lock switch or the LOCK button on the transmitter.
The BCM enters the standby mode when the above conditions are detected. If a door was already opened when the arm mode was requested, the standby mode does not start the timer until the last door is closed.
When the last door is closed, a 15 second timer is activated. Once the timer has expired, the BCM enters the armed mode. After this delay, any forced entry activates the alarm mode.
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 This is followed by a three minute time-out with the horn no longer active.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.

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 via serial data to perform the appropriate arm/disarm functions.

Security Indicator

The security indicator is illuminated by the instrument panel cluster (IPC) based on information (via serial data) from the BCM for CTD, or theft deterrent module (TDM) for immobilizer. The CTD system uses the security indicator to inform the driver of system status prior to arming. The security indicator on the instrument cluster is controlled by both the CTD system and the immobilizer system.

The CTD system, integral to the BCM, commands the IPC to control the security indicator only when the ignition switch is OFF. The CTD system uses the indicator to identify system status.
The immobilizer system, integral to the theft deterrent module (TDM) or the RCDLR when the vehicle has keyless entry, commands the IPC to control the security indicator only when the ignition switch is ON as a malfunction indicator. The immobilizer system is to deter vehicle theft. Refer to Immobilizer Description and Operation for more information on the immobilizer system.

Door Ajar Switches

The CTD system uses the door ajar switches as a status indicator to activate the alarm. The door ajar switches are monitored by the BCM via a discrete input from each door ajar switch. If the BCM receives a signal indicating a door is opened when the CTD system is armed, the BCM activates the alarm.

Driver Door Key Cylinder Switch

The CTD system uses the driver door cylinder switch as a means to disarm the CTD system. The BCM receives the status of the driver door cylinder switch based on a discrete input from the switch. When the driver door key cylinder is rotated the CTD system will immediately disarm.

Hood Ajar Switch

The CTD system uses the hood ajar switch as a status indicator to activate the alarm. The BCM monitors the hood ajar switch via a discrete input from the switch. If the BCM receives a signal indicating the hood has been opened when the CTD system is armed, the BCM activates the alarm.

Rear Compartment Lid Ajar Switch

The CTD system uses the rear compartment ajar switch as a status indicator to activate the alarm. The BCM monitors the rear compartment ajar switch via a discrete input from the switch. If the BCM receives a signal indicating the rear compartment has been opened when CTD system is armed, the BCM activates the alarm.

Inputs

The BCM monitors the following inputs for CTD:

The door ajar switches
Driver door cylinder switch
The keyless entry transmitter LOCK/UNLOCK buttons; a serial data message from the RCDLR
The immobilizer status-The BCM uses the immobilizer status for disarming the system or silencing an alarm when the correct vehicle key is used to start the vehicle
The rear compartment ajar switch
The hood ajar switch

Outputs

The BCM controls the following for CTD:

The horn relay
The exterior lamps