Service Information

Orlando

DTC B3935

Diagnostic Instructions

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

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

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

DTC Descriptor

DTC B3935 00: Transponder Authentication Error

When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the key is energised by the exciter coils surrounding the ignition lock cylinder. The transponder transmits a signal to the body control module (BCM). The BCM then compares this value to a value stored in memory. If the value is correct, the BCM will send the prerelease password via the serial data circuit to the engine control module (ECM). If the learned key code does not match or a transponder value is not received, the BCM will send the start disable password to the ECM.

With BTM/ATH

When a keyless entry transmitter is inserted into the transmitter pocket/slot and the ignition mode switch is pressed, the transponder embedded in the transmitter is energised by the immobiliser aerial exciter coil. The transponder transmits a signal to the body control module (BCM). The BCM then compares this value to a value stored in memory. If the value is correct, the BCM will send the prerelease password via the serial data circuit to the engine control module (ECM). If the learned key code does not match or a transponder value is not received, the BCM will send the start 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 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 centre 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

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Replace the suspected inoperative or malfunctioning key.
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
All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Key with Integrated Transmitter Programming

•	Control Module References for BCM replacement, setup, and programming