CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 143

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Overview

ISX – Engine Oil Rifle Pressure 1 SMALL | MEDIUM | LARGE

ISM – Engine Oil Rifle Pressure 1 SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) provides a 5 volt supply to the engine oil pressure sensor on the sensor supply 1 circuit. The ECM also provides a ground on the sensor return circuit. The engine oil pressure sensor provides a signal to the ECM on the engine oil pressure sensor signal circuit. This sensor signal voltage changes based on the pressure in the oil rifle. The ECM will detect a low signal voltage at operating conditions when the oil pressure may be slightly lower. The ECM will detect a high signal voltage during high engine speeds or operating conditions when the oil temperature is low.

If the ECM detects low signal voltage indicating a low engine oil pressure, this fault code sets.

Component Location

The engine oil pressure sensor is located on the left side of the engine block. 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 engine oil pressure is less than 55 kPa [8 psi] at 800 rpm for more than 5 seconds.

Action Taken When the Fault Code is Active

• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
• A torque derate issued by the ECM limiting the power output of the engine.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light and the torque derate will be removed when the oil pressure reading is detected to be within the normal operating range.

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.

This fault code goes active when the engine oil pressure drops below the engine protection limit. Troubleshoot the engine for low oil pressure.

Refer to Troubleshooting Fault Code t05-143