Yale 110-3 – Engine Control Unit (ECU) / Engine Controller: Coolant Temperature Sensor OORH

The voltage signal coming from the engine coolant temperature sensor is exceeding the maximum expected threshold (e.g., reading greater than 4.8V). This indicates an open circuit, a short to a 5V source or battery voltage, internal sensor failure, or a malfunctioning input within the engine controller.

• Yale and Hyster Forklifts
• Yale VX Series
• GC-VX
• GLC-VX
• GDP-VX
• GLP-VX
• Hyster FT Series

1. 1

   Wait for the engine to cool down completely before inspecting the cooling system.

2. 2

   Check the coolant temperature sensor, its connector, and the wire harness for physical damage, loose connections, or corrosion.

3. 3

   Check the power and ground at the sensor, and perform continuity and resistance tests on the coolant sensor wiring to check for open circuits or shorts to battery voltage.

4. 4

   Check the live status of the fault code using diagnostic software and verify if the sensor voltage is stuck above the threshold (e.g., >4.8V).

1. 1

   Secure Connections

   Inspect and firmly secure the connections between the sensor and the engine controller harness.

2. 2

   Repair Wiring

   If your multimeter tests indicate an open circuit or a short to battery voltage in the harness, repair or replace the damaged section of the wiring.

3. 3

   Replace Sensor

   If the wiring and connectors test good but the sensor output remains out of range (indicating internal sensor failure), remove the old sensor and install a new OEM coolant temperature sensor.

4. 4

   Clear Codes

   Reconnect the battery, clear the fault codes from the system using the onboard dash menu or a diagnostic handset, and monitor the live sensor readings.

5. 5

   Controller Evaluation

   If the problem persists after verifying the wiring and replacing the sensor, the engine controller's coolant temperature input is likely malfunctioning. Consider ECU repair or replacement.