GM Service Manual Online
For 1990-2009 cars only

Theft System Description and Operation

The theft deterrent system on this vehicle is comprised of two separate systems, the vehicle theft deterrent (VTD) system and the optional 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 instrument cluster illuminates the SECURITY indicator in the message center as determined by the VTD and CTD systems. The instrument cluster receives a class 2 message from the BCM in order to control the indicator.

    • 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.

Keyless Entry System

The keyless entry system functions interact with the content theft deterrent system but is diagnosed as a stand-alone system. Refer to Keyless Entry System Description and Operation in Keyless Entry.

Radio with TheftLock

The theft deterrent system does not interact with radio theftlock equipped vehicles. Radio theftlock is diagnosed as a stand-alone system. Refer to Radio/Audio System Description and Operation in Entertainment.

CTD/VTD Description and Operation

Refer to one of the following:

    • For CTD information refer to Content Theft Deterrent (CTD) Description and Operation .
    • For VTD information refer to Vehicle Theft Deterrent (VTD) Description and Operation .