CM2150 Electronic Control System – FAULT CODE 556

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Overview

ISC and ISL CM2150 – Crankcase Pressure Sensor Circuit SMALL | MEDIUM | LARGE

Circuit Description

The pressure inside the crankcase is measured by the crankcase pressure sensor. When the crankcase pressure sensor determines that the crankcase pressure is higher than normal, this fault code is logged.

Component Location

The crankcase pressure sensor is located near the crankcase breather filter. Use the following procedure for a detailed component location view.Refer to Procedure 100-002 in Section F.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the engine speed is greater than 500 rpm.

Conditions for Setting the Fault Codes

The ECM detects that the crankcase pressure is greater than a calibrated value.

Action Taken When the Fault Code is Active

• The ECM illuminates the red STOP ENGINE light when the crankcase pressure limit is exceeded.
• The engine torque output will be reduced to protect the engine from excessive crankcase pressure.

Conditions for Clearing the Fault Code

The ECM will turn off the red STOP ENGINE light as soon as the crankcase pressure drops below a calibrated value.

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. Use the following procedure in the corresponding Troubleshooting and Repair Manual for the engine being serviced.Refer to Procedure 019-032 in Section 19.

Possible causes of this fault code include:

• Crankcase breather filter needs to be replaced
• Crankcase pressure sensor damage
• Plugged or restricted crankcase breather oil separator
• Plugged or restricted crankcase breather oil drain tube or check valve
• Plugged or restricted crankcase breather draft tube
• Frozen, plugged, or restricted crankcase breather tube.

It is important to check for plugged or restricted hoses, tubes, check valves, oil separator, and filters in extreme cold ambient temperatures.

If Fault Code 556 becomes active due to a plugged filter before the maintenance interval is reached or the filter plugs frequently, see the Crankcase Gases (Blowby) Excessive troubleshooting symptom tree.

After Fault Code 556 occurs, it is important to check for progressive damage to the engine due to the high crankcase pressure. Check for oil leaking from gaskets and seals.

Refer to Troubleshooting Fault Code t05-556