CM2150 Electronic Control System – FAULT CODE 252

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Overview

ISB, ISC, and ISL – Oil Level Sensor Circuit SMALL | MEDIUM | LARGE

Circuit Description

The oil level sensor will monitor the oil fluid level in the oil pan at key-on. The oil level sensor will not monitor the oil level after the engine is started or when the engine speed is greater than 0 rpm. During engine key-on, if the oil level sensor detects a critical low oil level, then the amber CHECK ENGINE lamp will blink for 30 seconds and a fault code will be logged. If an operator observes a blinking amber CHECK ENGINE lamp at key-on, the operator must check the engine oil level with the manual dipstick.

The oil level sensor provides the ECM with a pulse width modulated (PWM) signal. Within this signal, the oil level sensor transmits the engine oil level reading, oil temperature, and fault code information from the oil level sensor.

Component Location

The oil level sensor is located on the left side of the engine on the front part of the dipstick port. Refer to Procedure 100-002 (Engine Diagrams) in Section F for a detailed component location view.

Conditions for Running the Diagnostics

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

Conditions for Setting the Fault Codes

A valid PWM message is not received from the oil level sensor within the required time limits at initial key-on.

Action Taken When the Fault Code is Active

• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
• The oil level sensor operation will be disabled.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light and enable oil level sensor operation immediately after a valid PWM signal is received from the oil level sensor.

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:

• The oil level sensor is not receiving power from the ECM. This could be caused by an open circuit in the power supply or low voltage supplied by the primary engine ECM
• Open return circuit on the oil level sensor circuit between the engine ECM and the oil level sensor
• Open or short circuit on the oil level sensor signal circuit between the ECM and oil level sensor
• A damaged oil level sensor.

Refer to Troubleshooting Fault Code t05-252