2010 Cadillac CTS Sedan AWD V6-3.6L Page 648

2010 Cadillac CTS Sedan AWD V6-3.6L Page 648

DTC B3935

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an 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. This stored value is the

learned key code. If the value is correct, the TDM will send the prerelease password via the serial data circuit to the engine control module (ECM).

If the transponder value does not match the learned key code or a transponder value is not received, the TDM 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 TDM memory.

* The transponder calculation to the challenge from the TDM does not match the TDM calculation.

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 a valid transponder value has been read and authenticated.

* A history DTC will be cleared after 100 malfunction-free ignition cycles or when a scan tool is used to clear DTCs.

Reference Information

Schematic Reference

Immobilizer Schematics (See: Accessories and Optional Equipment/Antitheft and Alarm Systems/Diagrams/Electrical Diagrams/Immobilizer

Schematics)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views)

Description and Operation

Immobilizer Description and Operation (without Y41) (See: Accessories and Optional Equipment/Antitheft and Alarm Systems/Description and

Operation/Immobilizer Description and Operation (Without Y41))Immobilizer Description and Operation (with Y41) (See: Accessories and

Optional Equipment/Antitheft and Alarm Systems/Description and Operation/Immobilizer Description and Operation (With Y41))

Electrical Information Reference

* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)

* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)

* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit

Testing/Testing for Intermittent Conditions and Poor Connections)

* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)

Scan Tool Reference

Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information