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 Telltale

The SECURITY Telltale on the message center is controlled by both the VTD system and the CTD system. The SECURITY telltale is controlled by both the theft deterrent control module and body control module through the serial data line.

    • The VTD system commands the instrument cluster to control the SECURITY telltale only when the ignition switch is ON. The VTD system uses the telltale 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 SECURITY telltale to identify system status.

Theft Lock Radio (if applicable)

Refer to Diagnostic Starting Point - Entertainment in Entertainment.

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