CM850 Electronic Control System – FAULT CODE 195 – Three Wire Sensor

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Overview

Engine Coolant Level Sensor 1 Circuit SMALL | MEDIUM | LARGE

Circuit Description

The electronic control module (ECM) supplies a 5 volt supply to the engine coolant level sensor using a common sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The engine coolant level sensor provides a signal to the ECM on the engine coolant level sensor signal circuit. This sensor signal voltage changes based on the coolant level in the expansion tank.

Component Location

The engine coolant level sensor is typically located in the radiator top tank or surge tank. Refer to the OEM troubleshooting and repair manual for location.

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 coolant level signal voltage is greater than 4.5-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.
• No engine protection will be available for low coolant level.

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

Possible causes of this fault code include:

• Open return circuit in the engine harness, connectors, or sensor
• Signal circuit shorted to sensor supply or battery voltage
• Sensor supply circuit shorted to battery voltage.

Refer to Troubleshooting Fault Code t05-195