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 P1380: Misfire Detected - Rough Road Data Not Available

### Circuit/System Description

Correct engine misfire detection is dependent on whether or not the vehicle is experiencing a rough road condition. A rough road condition causes unexpected crankshaft fluctuations. In order to detect a rough road condition, the electronic brake control module (EBCM) communicates a wheel speed signal over the serial data circuit to the engine control module (ECM). The wheel speed sensor information allows the ECM to distinguish if the crankshaft speed variations are caused by a rough road condition or are caused by a true misfire.

### Conditions for Running the DTC

• | The engine is operating.

• | DTC P1380 runs continuously once the above conditions are met for greater than 5 seconds.

### Conditions for Setting the DTC

• | The ECM detects an engine misfire while the rough road signal is unavailable.

• | The condition exists for greater than 4 seconds or a cumulative of 30 seconds.

### Action Taken When the DTC Sets

DTC P1380 is a Type C DTCs.

### Conditions for Clearing the DTC

DTC P1380 is a Type C DTCs.

### Reference Information

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Start and idle the engine, observe the DTC information with a scan tool. DTC P1380 should not set.

Note: If any UXXXX DTCs are set, diagnose those first.

⇒ | If DTC P1380 failed this ignition, refer to Diagnostic Starting Point - Antilock Brake System.

2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module replacement, setup, and programming