Yale 522603-3 – Engine Control Module (ECM / ECU): Fuel Temp (LPG) Sensor OORH

The voltage signal from the LPG Fuel Temperature Sensor is Out Of Range High (OORH), exceeding normal operating parameters. This is typically caused by an open circuit in the sensor return or signal wire, the signal wire being shorted to a 5V reference or battery voltage, an internal failure of the sensor, or a functional failure within the controller's input circuitry.

• Yale and Hyster Forklifts
• Yale Veracitor VX series (GLC030VX, GLC040SVX, GLP/GDP16-20VX)
• Hyster Fortis series (S40-70FT, H60FT)
• Trucks equipped with Mazda 2.0L / 2.2L LPG engines
• Trucks equipped with GM 2.4L / 4.3L LPG engines

1. 1

   Visually inspect the fuel temperature sensor wiring harness and connectors (specifically check plug 234) for physical damage, breaks, corrosion, or loose connections.

2. 2

   Use a multimeter to check for an open circuit in the wiring harness, and test for a short circuit between the sensor signal wire and the 5V reference or battery voltage.

3. 3

   Check the sensor's resistance at operating temperatures to see if it is out of specification.

4. 4

   If the wiring and sensor test good, test the ECM/controller sensor inputs to rule out a malfunctioning engine control module.

1. 1

   Depressurize the Fuel System

   Close the shutoff valve on the LPG tank. Run the engine until the fuel in the lines is completely consumed and the engine stalls. If the engine will not run, ensure the valve is tightly closed and work in a well-ventilated area away from sparks.

2. 2

   Disconnect Power

   Disconnect the forklift's battery to prevent electrical shorts and clear volatile memory.

3. 3

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed broken or shorted wires, repair the wiring harness or replace the damaged connector terminals.

4. 4

   Replace the Sensor

   Locate the Fuel Temperature Sensor (typically mounted on or immediately adjacent to the EPR - Electronic Pressure Regulator assembly). Disconnect the wiring plug, unthread the faulty sensor, and install the replacement unit.

5. 5

   Reassemble and Restore Power

   Reconnect the sensor wiring harness. Open the LPG tank valve slowly and check for leaks. Reconnect the battery.

6. 6

   Clear Codes and Verify

   Turn the ignition on, clear the fault codes using the onboard display or a PC Service Tool, and start the engine. Monitor the live sensor data to verify the voltage is now within the normal range. (If the code immediately returns and the sensor/wiring are brand new, the ECM must be replaced).