GM Service Manual Online
For 1990-2009 cars only

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 condition is 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 50 seconds.

Action Taken When the DTC Sets

DTC P1380 is a Type C DTC.

Conditions for Clearing the MIL/DTC

DTC P1380 is a Type C DTC.

Diagnostic Aids

The following table illustrates the ECM connector locations:

ECM Connector Location

X2

X1

Front of Vehicle

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Ignition ON, observe the diagnostic trouble code (DTC) information with a scan tool. Verify there are no communication DTCs set.
  2. If there are communication DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
  3. Engine idling, observe the scan tool DTC information. DTC P1380 should not set.
  4. If the DTC failed this ignition, refer to Diagnostic Starting Point - Antilock Brake System.
  5. 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 are captured in the Freeze Frame/Failure Records Data List.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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