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Vehicle Theft Deterrent (VTD) Operation
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 unique value, which is received by the VTD Controller Module . The VTD Controller Module then compares this value to a value stored in memory and performs one of the following functions:
If the transponder value is correct, the VTD Controller Module sends a class 2 message containing the module's unique enable password to the PCM.
If the transponder value is incorrect, the VTD Controller Module sends a class 2 message containing a disable password to the PCM.
If the VTD Controller Module is unable to measure the ignition key transponder value for one second, due to a damaged or missing pellet or a damaged exciter, the VTD sends a class 2 message containing a disable password to the PCM
Important
If the VTD Controller Module is unable to measure the ignition key transponder value for 30 consecutive seconds, after the vehicle has started, the module will consider itself malfunctioning and enter a fail enable state and illuminate the Security Indicator. The vehicle will not stall or stop running. If the VTD Controller Module is in a fail enable state when the ignition is turned to OFF, it will remain fail enabled until the next time the vehicle is started. If the VTD Controller Module is fail enabled the Pass Key® III system is NOT active and the vehicle will start. The module WILL send its enable password even if a transponder value is not received. The VTD Controller Module will remain fail enabled until the module measures a valid key transponder value.
When the PCM receives a password from the VTD Controller Module, the PCM compares the password to a password stored in its memory (learned password) and performs one of the following functions:
If the PCM receives a correct system enable password, indicating a learned VTD Controller Module has a read a valid transponder value, fuel and starting are enabled.
If the PCM receives a system disable password, indicating a VTD Controller Module has a read an invalid transponder value, fuel and starting are disabled.
If the PCM receives an incorrect password, indicating a VTD Controller Module that has not been learned by the PCM, fuel and starting are disabled.
If the PCM has no communication with the VTD Controller Module, fuel and starting are disabled.
Important
If the PCM is unable to communicate with the VTD Controller Module (loss of class 2 state of health) after the vehicle has started, the module will consider itself malfunctioning and enter a fail enable state and illuminate the Security Indicator. The vehicle will not stall or stop running. If the PCM is in a fail enable state when the ignition is turned to OFF, it will remain fail enabled until the next time the vehicle is started. If the PCM is fail enabled the Pass Key® III system is NOT active and the vehicle will start. The PCM will remain fail enabled until class 2 communication with the VTD Controller Module is restored.
SECURITY Indicator Operation
The VTD Controller Module can command the instrument cluster to illuminate the SECURITY indicator only when the ignition key is in the ON position. If the PCM loses communication with the VTD Controller Module, the instrument cluster will also detect the loss of communication and will illuminate the SECURITY indicator. The SECURITY indicator can indicate both malfunctions - the indicator on steady, and tamper - the indicator flashes indicating unauthorized operation. Under the following conditions the SECURITY indicator may be commanded to illuminate.
SECURITY Indicator Stays Illuminated and Engine Starts
If the VTD Controller Module was unable to measure the ignition key transponder value or the PCM lost communication with the VTD Controller Module while the engine was last running, the indicator will remain illuminated during subsequent ignition cycles. This is to remind the driver that the vehicle theft deterrent system will not be functioning until the problem is corrected. The vehicle is fail enabled and will start.
SECURITY Indicator Illuminates when Engine is Running
If the VTD Controller Module is unable to measure the ignition key transponder value or the PCM loses communication with the VTD Controller Module while the engine is running, the indicator will be illuminated. If the key is turned to OFF, the vehicle will be fail enabled and will start if the condition still exists at the next attempt to start the vehicle.
SECURITY Indicator Illuminated and Engine Does Not Start
The VTD Controller Module or the PCM has detected a problem with the PASS-Key® III system. The VTD Controller Module is unable to measure the ignition key transponder value. The System is in Learn Mode, refer to Programming Theft Deterrent System Components .
SECURITY Indicator Flashes and Engine Does Not Start
The VTD Controller Module has measured an incorrect transponder value when the ignition key is turned to the ON position. The transponder has not been learned by the VTD Controller Module. This is considered a tamper condition by the Module.
SECURITY LED
The VTD controller Module commands the instrument cluster to illuminate the theft LED located in the interior dimming switch. The instrument cluster receives a class II message from the VTD controller module to control this LED. It is intended to be used as another theft deterrent and indicate that the VTD system is in the ARMED state of readiness.
