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 P1631: Theft Deterrent Fuel Enable Signal Not CorrectCircuit/System Description
The theft deterrent module (TDM) sends the fuel enable password to the engine control module/powertrain control module (ECM/PCM) via the serial data circuit. The ECM/PCM compares this password to the learn password. If the learned password matches the password received from the TDM, the ECM/PCM will allow vehicle starting.
Conditions for Running the DTC
Ignition is in the ACCESSORY or RUN position.
Conditions for Setting the DTC
The ECM/PCM receives an incorrect fuel enable password from the TDM.
Action Taken When the DTC Sets
| • | The security indicator will illuminate. |
| • | Vehicle starting will be disabled. |
Conditions for Clearing the DTC
| • | A current DTC will be cleared when a correct fuel enable password is received. |
| • | A history DTC will be cleared after 40 malfunction-free ignition cycles. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Immobilizer Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Important: Because of normal system communications between the TDM and ECM, any theft deterrent B-codes must be diagnosed prior to the diagnosis of P-codes.
Perform the 10-Minute Immobilizer Relearn procedure. Refer to Immobilizer System Component Programming . The ECM/PCM should successfully complete the password learn and the vehicle should start.
| ⇒ | If the ECM/PCM does not complete the learn or vehicle starting remains disabled, replace the ECM/PCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for ECM/PCM replacement, setup and programming
