GM Service Manual Online
For 1990-2009 cars only

Theft System Description and Operation

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 system 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 grounding the security indicator control circuit.

    • The VTD system commands the instrument cluster to control the indicator only when the ignition switch is ON. The VTD system uses the indicator as a malfunction indicator.
    • The CTD system commands the instrument cluster to control the indicator only when the ignition switch is OFF. The CTD system uses the indicator to identify system status.

CTD Description and Operation

Refer to Content Theft Deterrent (CTD) Description and Operation for specific system description and operation.

VTD Description and Operation

Refer to Vehicle Theft Deterrent (VTD) Description and Operation for specific system description and operation.