DTC Descriptor
DTC B3935 57 : Transponder Key Identification
Error
Diagnostic Fault Information
Perform the
Diagnostic System Check - Vehicle
.
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 energised by the
exciter coils surrounding the ignition lock cylinder. The energised 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 sends the start enable
password via the serial data circuit to the engine control module (ECM). If either
the transponders unique value or the calculation to the challenge is incorrect, the
TDM will send the start disable password to the ECM.
Conditions for Running the DTC
| • | Ignition is in the ACC or ON position. |
| • | A valid transponder value has been read but not authenticated. |
Conditions for Setting the DTC
| • | The transponder value is invalid or does not match the value stored in
the TDM memory. |
| • | The transponder calculation to the challenge from the TDM does not match
the TDMs calculation. |
Action Taken When the DTC Sets
| • | Vehicle starting will disable. |
| • | The security warning lamp will illuminate. |
Conditions for Clearing the DTC
| • | A current DTC will clear when a valid transponder value has been read
and authenticated. |
| • | A history DTC will clear after 100 fault-free ignition cycles. |
| • | The DTC can be cleared using a scan tool. |
Reference Information
Description and Operation
Theft Systems Description and Operation
Scan Tool Reference
Control Module References
Circuit/System Testing
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
.
