B3935

DTC B3935

Diagnostic Instructions

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

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B3935 00

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Transponder Authentication Error

Circuit/System Description

When an ignition key is inserted into the transmitter slot and the ignition mode is changed, 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 body control module (BCM). The BCM then compares this value to a value stored in memory. If the value is not correct, the BCM disables engine start.

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 and matches the value stored in the BCM memory.

* The transponder calculation of the challenge from the BCM does not match the BCM calculation.

Action Taken When the DTC Sets

* Vehicle starting will be disabled.

* The security indicator will illuminate. The driver information center will display a service message.

Conditions for Clearing the DTC

* A current DTC will be cleared when a valid transponder value has been read and authenticated.

* A history DTC will be cleared after 100 malfunction-free ignition cycles.

Reference Information

Schematic Reference

Immobilizer Schematics Immobilizer Schematics

Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1

Description and Operation

Immobilizer Description and Operation Immobilizer

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Programming and Relearning for scan tool information

Circuit/System Verification

1. Replace the suspected inoperative or malfunctioning key.

2. Verify DTC B3935 is not set as current.

• If the DTC is set as current

Replace the K9 BCM.

• If the DTC is set as history

3. All OK.

Repair Instructions

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

* Key with Integrated Transmitter Programming Programming and Relearning

* Control Module References Programming and Relearning for BCM replacement, setup, and programming