CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 1928

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Overview

ISX – Aftertreatment 1 Fuel Pressure Sensor Circuit SMALL | MEDIUM | LARGE

ISM – Aftertreatment 1 Fuel Pressure Sensor Circuit SMALL | MEDIUM | LARGE

Circuit Description

The aftertreatment fuel pressure sensor is used to monitor the fuel pressure into the aftertreatment system. The electronic control module (ECM) supplies the aftertreatment fuel pressure sensor a 5 volt reference voltage. When the fuel pressure is low, the sensor signal voltage is low. When the fuel pressure is high, the sensor signal voltage is near the 5 volt reference voltage. The ECM monitors the aftertreatment fuel pressure signal circuit voltage to calculate the pressure of the fuel within the aftertreatment system.

Component Location

The aftertreatment fuel pressure sensor is located in the aftertreatment shutoff valve assembly. 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 aftertreatment fuel pressure signal voltage is less than 0.2-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 calculated value of aftertreatment fuel pressure is used for aftertreatment operation.

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.

Possible causes of this fault code include:

• Open signal circuit in the engine harness, connector, sensor.
• Signal wire shorted to ground.
• A shorted sensor.

Refer to Troubleshooting Fault Code t05-1928