CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 546

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Overview

ISX – Fuel Delivery Pressure Sensor SMALL | MEDIUM | LARGE

Circuit Description

The fuel delivery pressure sensor responds to pressure changes in the fuel manifold of the integrated fuel system module. The fuel delivery pressure sensor has a 5-VDC supply circuit, a sensor signal voltage, and a return circuit.

The electronic control module (ECM) provides a 5-VDC supply to the fuel delivery pressure sensor using a common sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The fuel delivery pressure sensor provides a signal to the ECM on the fuel deliver pressure sensor signal circuit. This sensor signal voltage changes based on the pressure in the fuel manifold. The ECM will detect a low signal voltage at operating conditions such as during an idle or a deceleration. The ECM will detect a high signal voltage during high engine load operating conditions.

Component Location

The rail fuel pressure sensor is located on the bottom front corner of the integrated fuel system module. Refer to Procedure 100-002 (Engine Diagrams) in Section E for a detailed component location view.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes

The ECM detects that the fuel delivery pressure signal voltage is greater than 4.92-VDC for more than 1 second.

Action Taken When the Fault Code is Active

• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
• A default value for the fuel delivery pressure reading is used.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.

Shop Talk

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM. Refer to Procedure 019-032 (ECM Calibration Code) in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.

The rail fuel pressure sensor shares supply and return wires in the engine harness with other sensors. Opens and shorts in the engine harness can cause multiple fault codes to be active. Before troubleshooting Fault Code 546, check for multiple faults.

Possible causes of this fault code include:

• Open return circuit in the engine harness, connectors, or sensor.
• Signal circuit shorted to sensor supply or battery voltage.
• Sensor supply circuit shorted to battery voltage.

Refer to Troubleshooting Fault Code t05-546