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 P1630: Theft Deterrent Learn Mode Active

### Circuit/System Description

When replacing a theft deterrent module (TDM), the engine control module (ECM) must learn the new fuel continue password from the replacement TDM. If the ECM is replaced with a service replacement part, it is in a functional state to automatically learn the vehicle fuel continue password. If the TDM is replaced, the ECM must be placed in learn mode so it can learn the new TDM password. This DTC indicates the ECM is in a functional state to learn the TDM start enable password.

### Conditions for Running the DTC

The ECM is in learn mode.

### Conditions for Setting the DTC

DTC P1630 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 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.

### 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

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 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 after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming