Diagnostic Instructions
DTC Descriptor
DTC B3935: 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 fuel continue
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 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. |
Reference Information
Schematic Reference
Immobilizer Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References
for scan tool information
Circuit/System Verification
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.
