Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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 module (TDM). The TDM then compares this value to a value stored in memory. If the values match, the TDM will send the fuel enable password via the serial data circuit to the engine control module (ECM). If the transponders unique value is incorrect, the TDM will send the fuel disable password to the ECM.

The transponder value is valid but does not pass authentication.

Schematic Reference

Theft Deterrent System Schematics

Connector End View Reference

Theft Deterrent System Connector End Views

Description and Operation

Vehicle Theft Deterrent (VTD) Description and Operation

Electrical Information Reference

Scan Tool Reference

1. Verify that DTC B3055 or DTC B3060 is not set as a current DTC.

⇒	If DTC B3055 or DTC B3060 is set, proceed with those diagnostic prior to performing the diagnostics for DTC B3935. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

2. Replace the suspected inoperative or malfunctioning key. DTC B3935 should not reset and the vehicle should start.

⇒	If the replacement key results in the resetting of DTC B3935, replace the TDM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Important: Because of how vehicle key information and theft deterrent passwords are stored within the TDM, the Set Up a New Theft Deterrent Module procedure must be performed prior to the removal and replacement of the TDM if the vehicle keys are being reused. Performing the setup procedure first allows the scan tool to extract the key information and passwords from the old TDM prior to its removal. Failure to perform this step will result in the failure to learn the existing vehicle keys and new vehicle keys will be required when replacing the TDM.