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DTC P0318 (LLU)

DTC P0318 (LLU)

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 P0318 00

Rough Road Sensor Circuit

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. If the EBCM reports a wheel speed sensor malfunction, or the ECM does not receive the rough road information, this DTC sets.

Conditions for Running the DTC


• The engine speed is between 1 520-4 000 RPM.

• The engine coolant temperature (ECT) is warmer than -48°C (-54°F).

• The ignition voltage signal is greater than 10.5 V.

• This DTC runs continuously within the enabling conditions.


Conditions for Setting the DTC

The EBCM reports a wheel speed sensor fault to the ECM.

or

The ECM does not receive communication of a rough road signal from the EBCM for greater than 5 s.

Action Taken When the DTC Sets


• DTC P0318 00 is a Type C DTC.

• The service vehicle soon indicator will illuminate.


Conditions for Clearing the DTC

DTC P0318 00 is a Type C DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

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 Testing


1.
Note

If any U DTCs are set, diagnose those first.


Engine idling, observe the scan tool DTC information.

2. If DTC P0318 00 failed this ignition, refer to Diagnostic Starting Point - Vehicle .


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming