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
- Transponder Authentication Error

Circuit/System Description

When an ignition key is inserted into the ignition lock cylinder 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 (Connector End Views By Name)
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

If DTC B3935 is set, replace the suspected inoperative or malfunctioning key. If the DTC resets, replace the K9 Body Control Module.

Repair Instructions

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

* Replacing Keys (Replacing Keys)
* Control Module References (Programming and Relearning)for BCM replacement, setup, and programming