The vehicle theft deterrent (VTD) system functions are provided by the theft deterrent control module. The VTD system prevents vehicle operation if a valid - learned transponder PASS-Key III (PK3) ignition key is not used to start the vehicle. Vehicles with console mounted ignition switches have exciter modules separate from the theft deterrent control module with the vehicle wiring harness connecting the two. The PK3 key has a transponder embedded in the plastic head of the key. The exciter is an antenna which is made up of wire coils which surround the ignition lock cylinder. The powertrain control module (PCM)/engine control module (ECM) enables engine starting when it receives a valid - learned password from the theft deterrent control module via the serial data circuit. The components of the VTD system are as follows:

Vehicles with steering column mounted ignition switches have the exciter integral with the theft deterrent control module which is located within the steering column. Vehicles with instrument panel mounted ignition switches have exciter modules, separate from the theft deterrent control module, with the vehicle wiring harness connecting the two. The theft deterrent control module for vehicles with instrument panel mounted ignition switches is located within the instrument panel. The theft deterrent control module can learn up to 10 transponder values, or keys.

The theft deterrent control module uses the following inputs, battery voltage, ignition switched voltage, and ground circuit. The theft deterrent control module uses the following outputs, password exchange with the powertrain control module (PCM), via the class 2 serial data circuit.

When an ignition key is inserted into the ignition lock cylinder, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its value, which is received by the theft deterrent control module. The theft deterrent control module then compares this value to a value stored in memory and performs one of the following functions:

The powertrain control module (PCM)/engine control module (ECM) verifies that the password received from the theft deterrent control module, via the serial data circuit, is correct. The theft deterrent control module can learn only one enable password. If the enable password is correct, the PCM/ECM enables the starting and fuel delivery systems.

The PCM/ECM disables the starting and fuel delivery systems if any of the following conditions occur:

The ignition key for theft deterrent equipped vehicles is a typical looking ignition key with a transponder located in the plastic end of the key. The transponder value is fixed and unable to be changed. The theft deterrent system uses the ignition key transponder value to determine if a valid ignition key is being used to start the vehicle. There are approximately 3 trillion possible transponder values. There are no visible electrical contacts. The keys may be identified by the letters PK3 stamped into the steel shank of the key. The theft deterrent systems use the following types of ignition keys:

Master Keys

Master keys have a black plastic end for full access operation of the vehicle. Master keys may perform the following functions:

Valet Keys

Important: Vehicles may or may not come equipped with a valet key.

Valet keys have a gray plastic end for restricted operation of the vehicle. Valet keys may perform the following functions:

The ignition lock cylinder performs all of the functions of a lock cylinder on a non theft-deterrent equipped vehicle. The ignition lock cylinder is located in the vehicles center console. In this location, the exciter coils surround the ignition lock cylinder such that they are very close to the head of the key, which contains the transponder pellet.

If an ignition lock cylinder is replaced, new transponder keys must be cut to match the mechanical coding of the new lock cylinder. The new keys must be learned by the theft deterrent controller module. When replacing an ignition lock cylinder, refer to Ignition Switch Lock Cylinder Replacement .

The theft deterrent control module can command the instrument panel cluster (IPC) to flash the SECURITY indicator ON and OFF, or illuminate the SECURITY indicator ON steady, only when the ignition key is in the ON position. The body control module (BCM) can command the IPC to flash the SECURITY indicator ON and OFF, or illuminate the SECURITY indicator ON steady, only when the ignition key is in the OFF position. The security indicator does illuminate during the bulb check when the ignition is turned to ON for 5 seconds. If the powertrain control module (PCM) loses communication with the theft deterrent control module, the IPC will also detect the loss of communication and will illuminate the SECURITY indicator. The SECURITY indicator can indicate both malfunctions, indicator on steady and tamper, or indicator flashing, indicating unauthorized operation. Under the following conditions, the SECURITY indicator may be commanded to illuminate.