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 provide an overview of each diagnostic category.

### DTC Descriptor

DTC P1380 Misfire Detected - Rough Road Data Not Available

### Circuit Description

The engine control module (ECM) detects engine misfire events by monitoring the crankshaft deceleration variation. The ECM must distinguish the crankshaft deceleration caused by an actual engine misfire from deceleration caused by rough surface to monitor engine misfire correct. The ABS can detect if the vehicle is on the rough surface based on wheel acceleration or deceleration data supplied by wheel speed sensor. If the ABS detects a rough surface information exceeding the preset value, the information will be sent to the engine control module. The ECM uses the rough road information when calculating if the engine misfire. If the ABS can not detects rough road caused by a malfunction, engine misfire diagnosis will run continuously. But, if the engine misfire DTC has set, this DTC will set to indicate rough road data can not be received, or the ECM can not contact with the stop control module when the misfire is calculated because of the ABS malfunction.

### Conditions for Running the DTC

• | Rough road signal is lost.

• | Current DTC P0300 has set.

### Conditions for Setting the DTC

Rough road signal is lost.

### Action Taken When the DTC Sets

• | Do not illuminate MIL.

• | The ECM records the operating conditions at the time when the diagnostic test fails. The ECM displays the failure information in the Failure Records on the scan tool.

### Conditions for Clearing the MIL/DTC

• | The DTC becomes history when the conditions for setting the DTC are no longer present.

• | The history DTC is cleared after 40 malfunction free warm-up cycles.

• | The ECM receives the clear code command from the scan tool.

Step | Action | Value | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Component Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Monitor the ABS DTCs the scan tool displays. Are the ABS DTCs set? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Symptoms - Antilock Brake System