With ATH

DTC P0633 (with ATH)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor
DTC P0633
- Theft Deterrent Key Not Programmed

Circuit/System Description

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.

Conditions for Running the DTC

The ECM is in learn mode.

Conditions for Setting the DTC

DTC P0633 will set any time the ECM enters learn mode.

Action Taken When the DTC Sets

The security indicator will illuminate.

Conditions for Clearing the DTC

* 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.

Diagnostic Aids

The "key" referenced in the DTC descriptor does not refer to the vehicle key. In this case, "key" is referring to the challenge response.

Reference Information
Schematic Reference

Immobilizer Schematics Immobilizer Schematics
Connector End View Reference

Component Connector End Views Connector Views
Description and Operation

Immobilizer Description and Operation (with ATH) Immobilizer Description and Operation (with ATH)Immobilizer Description and Operation (without ATH) Immobilizer Description and Operation (without ATH)
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

Important: Because of normal system communications between the RCDLR 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 (with ATH) Immobilizer System Component Programming (with ATH)Immobilizer System Component Programming (without ATH) Immobilizer System Component Programming (without ATH). The ECM should successfully complete the password learn and the vehicle should start.

If the ECM does not complete the learn or vehicle starting remains disabled, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

Control Module References Control Module References for ECM replacement, setup, and programming