For 1990-2009 cars

### 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 P1649: Immobilizer Security Code Not Programmed

### Circuit/System Description

When learning the security code, as well as the challenge and response sequence, the engine control module (ECM) is placed in learn mode. Once the security code and challenge/response are learned, learn mode will be exited when the engine is successfully started.

### Conditions for Running the DTC

The ECM is in learn mode.

### Conditions for Setting the DTC

The ECM is not programmed.

### Action Taken When the DTC Sets

The security indicator in the instrument cluster will illuminate.

### Conditions for Clearing the DTC

• | A current DTC P1649 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.

### Reference Information

#### Schematic Reference

Immobilizer Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Immobilizer Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Note: Because of normal system communications between the body control module BCM and ECM, any immobilizer B-codes must be diagnosed prior to the diagnosis of P-codes. Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

Perform the Immobilizer Relearn procedure. Refer to Immobilizer System Component Programming. 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 K20 Engine Control Module (ECM).

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming