Were is anti theft module on Cadillac srx 2005
Vehicle Theft Deterrent (VTD) Description and Operation
The vehicle theft deterrent (VTD) system functions are provided by the theft deterrent control module. When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, 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 theft deterrent control module. The theft deterrent control module then compares this value to a value stored in memory, learned key code. If the value is correct the theft deterrent control module sends a random generated number to the transponder, this is called a challenge. Both the transponder and the theft deterrent control module perform a calculation on the challenge, if the calculations match the theft deterrent control module sends the fuel continue password via the serial data circuit to the Engine control module (ECM). If either the transponders unique value or the calculation to the challenge is incorrect the theft deterrent control module will send the fuel disable password to the ECM via the serial data circuit. The components of the VTD system are as follows:
• Theft deterrent control module
• Engine control module (ECM)
• Ignition key (Transponder)
• Ignition lock cylinder
• Security indicator
Theft Deterrent Control Module
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 ten keys (transponder values).
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 ECM, fuel continue/disable via the serial data circuit.
When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, 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 theft deterrent control module. The theft deterrent control module then compares this value to a value stored in memory, learned key code. If the value is correct the theft deterrent control module sends a random generated number to the transponder, this is called a challenge. Both the transponder and the theft deterrent control module perform a calculation on the challenge. The theft deterrent control module then performs one of the following functions:
• If both the transponder value and the calculation to the challenge are correct, the theft deterrent control module will send the fuel continue password to the ECM via the serial data circuit.
• If either the transponders unique value or the calculation to the challenge is incorrect the theft deterrent control module will send the fuel disable password to the ECM via the serial data circuit.
• If the theft deterrent control 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 theft deterrent control module will send the fuel disable password to the ECM via the serial data circuit.
Important: On some vehicles, If the VTD system is unable to read the ignition key transponder value after the vehicle has started, the VTD system will consider itself malfunctioning. The VTD system will enter a fail enable state and will command the security indicator to illuminate. When the VTD system is in a fail enable state the vehicle will NOT stall or stop running. If the VTD system is in a fail enable state when the ignition is switched OFF, the VTD system will remain fail enable until it is able to read a learned ignition key transponder value. When the VTD system is in a fail enable state the VTD system is NOT active and the vehicle will start. This feature is NOT available on all GM vehicle lines.
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