CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 227

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Overview

ISX – Sensor Supply 2 Circuit SMALL | MEDIUM | LARGE

ISM – Sensor Supply 2 Circuit SMALL | MEDIUM | LARGE

Circuit Description

The sensor supply 2 of the electronic control module (ECM) provides a 5 volt supply for the camshaft position sensor, exhaust gas pressure sensor, rail fuel pressure sensor, intake manifold pressure/temperature sensor, and crankcase pressure sensor on the ISX engine.

For ISM engines, the sensor supply 2 of the ECM provides a 5 volt supply for the camshaft position sensor, exhaust gas pressure sensor, intake manifold pressure/temperature sensor, and crankcase pressure sensor.

Component Location

The sensor supply 2 is located in the ECM. The supply voltage is spliced off in the engine harness to each sensor it supports.

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

The ECM detects that the sensor supply 2 signal voltage is more than 5.2-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 default value for the exhaust gas pressure sensor, intake manifold pressure sensor, and the crankcase pressure sensor is used.
• The backup camshaft position sensor will not be functional.

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.

High voltage on the (+) 5 volt supply line can be caused by a short to battery voltage in the engine harness or connectors, or a failed ECM.

Refer to Troubleshooting Fault Code t05-227