• | 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. |
When learning the prerelease password, as well as the challenge and response sequence, the engine control module (ECM) is placed in learn mode. DTC P0633 will set automatically as an indicator that the system is in learn mode and not as a fault indicator. Once the password and challenge/response are learned, learn mode will be exited when the engine is successfully started. If the ECM does not exit learn mode, P0633 will remain current and indicate a fault.
The ECM is in learn mode.
DTC P0633 will set any time the ECM enters learn mode.
The security indicator will illuminate.
• | A current DTC P0633 will be cleared upon a successful engine start after exit of learn mode. |
• | A history DTC will be cleared after 100 malfunction-free ignition cycles or when a scan tool is used to clear DTCs. |
The "key" referenced in the DTC descriptor does not refer to the vehicle key. In this case, "key" is referring to the challenge response.
Immobilizer Description and Operation
• | Circuit Testing |
• | Wiring Repairs |
Control Module References for scan tool information
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.
DTC P0633 will clear upon a successful engine start. Any malfunction that will cause a no-start condition will prevent DTC P0633 from clearing. Prior to diagnosing DTC P0633, ensure that all power moding and engine control systems are operating properly and all conditions that may cause a no-start have been corrected.⇒ | If not the specified value, refer to Power Mode Mismatch . |
⇒ | If the ECM does not complete the learn or vehicle starting remains disabled, replace the ECM. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for ECM replacement, setup, and programming