CM2150 Electronic Control System – FAULT CODE 1942

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Overview

ISB, ISC, ISL CM2150 – Crankcase Pressure Sensor SMALL | MEDIUM | LARGE

Circuit Description

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

Component Location

Use the following procedure for a detailed component location view of the crankcase pressure sensor and crankcase filter. Refer to Procedure 100-002 in Section E.

Conditions for Running the Diagnostics

The first part of this diagnostic runs at initial key ON and the second part runs when the engine is running.

Conditions for Setting the Fault Codes

The ECM detects that the crankcase pressure sensor is reading an erratic value at key ON or the crankcase pressure reading is not changing with engine operating conditions.

Action Taken When the Fault Code is Active

• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.

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, calibrate the ECM. Refer to Procedure 019-032 in Section 19.

This fault code can be caused by a crankcase breather hose disconnected between the engine outlet and the crankcase filter assembly on engines with an externally mounted crankcase filter option.

This check is only performed at keyswitch OFF, during the ECM powerdown. During this diagnostic check, the ECM monitors the value of the crankcase pressure sensor. If this value is outside of a specified range, Fault Code 1942 is set active at the next key ON.

Possible causes of this fault code include:

• Resistance in the wiring harness
• A malfunctioning in-range pressure sensor.

This fault code can be triggered if the crankcase pressure sensor is not installed correctly in the housing.

Refer to Troubleshooting Fault Code t05-1942