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: Rough Road Sensor CircuitCircuit/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 ignition is ON, or the engine is operating. |
| • | DTC P0318 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The EBCM reports a wheel speed sensor failure to the ECM. |
| OR |
| • | The ECM does not receive communication of a rough road signal from the EBCM for greater than 5 seconds. |
Action Taken When the DTC Sets
DTC P0318 is a Type C DTC.
Conditions for Clearing the MIL/DTC
DTC P0318 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
Connector End View Reference
Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, observe the diagnostic trouble code (DTC) information with a scan tool. Verify there are no communication DTCs set.
- Engine idling, observe the scan tool DTC information. DTC P0318 should not set.
- 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.
| ⇒ | If there are communication DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis. |
| ⇒ | If DTC P0318 sets, refer to Diagnostic Starting Point - Antilock Brake System for further diagnosis. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
