The Vehicle Theft Deterrent (VTD) system is a function
of the Theft Deterrent (VTD) module. When a ignition key is inserted into
the ignition lock cylinder, the reader exciter uses wire coils surrounding
the ignition lock cylinder to energize a transponder pellet located within
the plastic portion of the ignition key. The transponder when energized
transmits a unique value by radio frequency back to the reader exciter.
The reader exciter sends this value to the VTD module which then validates
this value against a value stored in memory and performs one of the following
functions:
| • | If the value does match the stored value the VTD sends the correct
pasword to the PCM via a class 2 message, the PCM enables fuel delivery to
the engine by activating the fuel injectors and the starter relay. |
| | Important: The VTD module and PCM operate in conjunction with each other to determine
fuel enable. A password is exchanged between the VTD module and PCM when the
VTD detects a valid key value over the class 2 serial data line. When
the PCM receives a password the PCM validates the password against a
password stored in memory and performs one of the following functions:
|
| - | If the password matches the PCM enables fuel delivery and activates
the starter relay. |
| - | If the password does not match the PCM disables fuel delivery,the
starter relay, and sets a DTC. |
| • | If the value does not match the stored value, the PCM disables
fuel delivery to the engine by disabling the fuel injectors, and does not
activate the starter relay. |
SECURITY Indicator Operation
The VTD module commands the instrument cluster to illuminate the SECURITY
indicator only when the ignition key is in the ON position. Under the following
conditions the VTD module commands the SECURITY indicator to illuminate.
Bulb Stays Illuminated and Engine Starts
If the indicator stays illuminated after the engine starts this indicates
that one of the following conditions has occurred:
| • | After the engine is running, the VTD module measures an invalid
transponder value for 30 consecutive seconds. The VTD module may allow the
engine to restart during this condition. |
| • | If the VTD module detects a problem while the engine was last
running the indicator illuminates until the problem is corrected. |
Bulb Stays Illuminated and Engine Does Not Start
The VTD module measures an invalid transponder value when the ignition
key is turned to the ON position.
Bulb Flashes and Engine Does Not Start
If the indicator flashes and the engine does not start, the VTD module
has detected a problem with the VTD system. During this mode of operation
the VTD module does not start the system disable interval.
