B3935

DTC B3935

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides and overview of each diagnostic category.

DTC Descriptor

DTC B3935 57
- Transponder Authentication Error

Circuit/System Description

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.

Conditions for Running the DTC

* Ignition is in the Accessory or Run position.
* A valid transponder value has been read.

Conditions for Setting the DTC

The transponder value is valid but does not pass authentication.

Action Taken When the DTC Sets

* Vehicle starting will be disabled.
* The security indicator will be illuminated.

Conditions for Clearing the DTC

* A current DTC will be cleared when the transponder calculation to the challenge matches that of the TDMs.
* A history DTC will be cleared after 100 malfunction-free ignition cycles or when a scan tool is used to clear DTCs.

Circuit/System Verification

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. Diagnostic Trouble Code Descriptions

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.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

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.

If the existing vehicle keys are not being reused, the TDM is to be replaced prior to performing of the setup procedure.

* Replacing Keys for replacing vehicle keys or adding keys when a learned master key is not available.
* Adding Keys for adding vehicle keys when a learned master key is available.
* Refer to Programing and Relearning Programming and Relearning