Yale 522598-3 – Engine Control Unit (ECU) / Controller: LPG Lock Off OORH

High-voltage electrical fault in the LPG (Liquid Petroleum Gas) lock-off valve circuit. Indicates the coil-to-ECU wiring harness is shorted to unswitched or switched battery voltage, the LPG lock-off solenoid coil has shorted turns, or there is a functional failure within the controller.

• Yale and Hyster Forklifts
• Yale VX series (GLP/GP/GDP 80-120VX)
• Yale 50MX
• Hyster FT series (H1.6-1.8FT, H2.0FTS, H30-35FT)

1. 1

   Inspect the wiring harness running from the ECU to the LPG lock-off valve for chafed wires, melted insulation, or pinched areas that could cause a short to battery voltage.

2. 2

   Disconnect the lock-off valve and use a multimeter to check the harness connector for improper voltage (short to switched or unswitched battery).

3. 3

   Measure the resistance of the LPG lock-off solenoid coil. If the resistance is out of specification, it indicates shorted turns and a faulty coil.

4. 4

   If the wiring harness and the solenoid coil both test good, verify the ECU for an internal functional failure.

1. 1

   Disconnect Power

   Turn off the forklift and disconnect the battery to prevent electrical shorts during repair.

2. 2

   Locate the Valve

   Locate the LPG lock-off valve, which is typically mounted near the LPG vaporizer/regulator or inline with the fuel hoses.

3. 3

   Disconnect Wiring

   Unplug the electrical connector from the LPG lock-off solenoid.

4. 4

   Repair Wiring (If Applicable)

   If the diagnostic tests revealed a short in the harness, repair or replace the damaged section of the wiring.

5. 5

   Replace Solenoid/Valve (If Applicable)

   If the coil has shorted turns, remove the retaining nut holding the solenoid to the valve stem and slide the old solenoid off. Install the new solenoid. (In some cases, the entire lock-off valve assembly may need to be replaced if it is a sealed unit).

6. 6

   Reassemble

   Reconnect the electrical connector and the battery.

7. 7

   Clear Codes

   Turn the ignition on and use the dash display or a diagnostic handset to clear the fault codes.

8. 8

   Test Run

   Start the engine and verify that the forklift stays running without shutting off or triggering the code again.