GM Service Manual Online
For 1990-2009 cars only

The theft deterrent system on this vehicle is comprised of 2 separate systems, the Vehicle Theft Deterrent (VTD) System and the Content Theft Deterrent (CTD) System. VTD prevents drive away theft by keeping the vehicle from starting. CTD is the vehicle alarm system which discourages unauthorized entry into the vehicle. These systems are described and diagnosed separately within this section.

Security Indicator

The security indicator on the instrument cluster is controlled by both the VTD System and the CTD System. The security indicator is controlled by the body control module (BCM) via a discrete output.

    • The VTD system commands the BCM to control the security indicator only when the ignition switch is ON. The VTD system uses the security indicator as a malfunction indicator.
    • The CTD system, integral to the BCM, controls the security indicator only when the ignition switch is OFF. The CTD system uses the indicator to identify system status.

CTD/VTD Description and Operation

Refer to the following for the appropriate description and operation:

    •  Content Theft Deterrent (CTD) Description and Operation
    •  Vehicle Theft Deterrent (VTD) Description and Operation