JLG Articulating Boom Lift 431 Fault Code: Fuel Sensor Short to Battery
Fuel Sensor Short to Battery · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Code 431 sets when the ground module detects a voltage higher than 2.50 volts on the fuel sensor input (J2-25). JLG describes this as a fuel sensor short to battery. The control system responds by shutting down all fuel level indicators in both the platform and ground stations.
Low severity. This fault does not stop machine operation or trigger a lockout. It disables fuel level readouts at both control stations, which is an operational inconvenience but not a safety-critical failure on its own. Diagnose it when convenient, but don't ignore it long term since running out of fuel unexpectedly can create its own hazards on a job site.
What does JLG Articulating Boom Lift error code 431 mean?
Fault code 431 is JLG's designation for a fuel sensor short to battery condition. The ground module monitors the fuel sensor input circuit at pin J2-25. When that circuit reads a voltage higher than 2.50 volts, the controller interprets it as a short to a higher voltage source, typically battery voltage bleeding onto the signal wire.
The fuel sender itself works like a variable resistor: as the float moves with fuel level, resistance changes, and that resistance is read by the control module as a voltage on the J2-25 circuit. If the wiring shorts to battery power, or the sender fails internally, the voltage seen by the module goes out of the expected working range and the fault sets.
Because the fuel gauge system is not tied to lifting, driving, or hydraulic function, this code is mainly an electrical instrumentation issue. It does affect your ability to know how much fuel is left, which matters for planning work and avoiding an unplanned shutdown mid-task.
What triggers a JLG Articulating Boom Lift 431 code?
The control module sets code 431 when it detects a voltage higher than 2.50 volts on the ground module fuel sensor input at J2-25.
Common causes of 431
- Fuel sender internally shorted or failed, causing resistance to fall outside the expected working range
- Wiring harness fault where the fuel sensor signal wire is shorted to a battery-voltage source
- Corroded, damaged, or loose connector at the fuel sender or at the ground module input pin J2-25
- Damaged insulation on the sensor wiring allowing contact with a powered circuit
How to troubleshoot JLG Articulating Boom Lift 431: first checks
- Disconnect the fuel sender and measure resistance across it. Expect a range from approximately 30 ohms (full) to 240 ohms (empty). If readings fall outside this range, replace the sender.
- With the fuel sender reconnected, back probe pin J2-25 and check voltage. Expect a range from approximately 0.5 volts to 2.3 volts. A reading outside this range, especially above 2.50 volts, confirms the fault condition.
- Inspect the wiring harness between the fuel sender and the ground module for chafed insulation, pinched wires, or contact with a power source that could cause a short to battery.
- Check the connector at the ground module input and at the sender for corrosion, loose pins, or moisture intrusion that could cause abnormal voltage readings.
How the code clears
No separate clearing step is listed. Once the sender is verified within its expected resistance range and the J2-25 circuit reads within the normal voltage window, the fault should stop being detected on its own. If the fault persists after confirming these readings, recheck the wiring harness for an intermittent short before replacing components.
Frequently asked questions
What does JLG fault code 431 mean?
It means the control module detected a voltage higher than 2.50 volts on the fuel sensor input circuit (J2-25), which JLG labels as a fuel sensor short to battery.
Will code 431 stop my boom lift from operating?
No. This fault only shuts down the fuel level indicators at the platform and ground stations. It does not disable boom, drive, or hydraulic functions.
How do I test the fuel sender for this fault?
Disconnect the sender and measure its resistance. It should read approximately 30 ohms when full and up to 240 ohms when empty. If it falls outside that range, replace the sender.
What voltage should I see at J2-25 if everything is working normally?
With the fuel sender connected, back probing J2-25 should show a voltage between approximately 0.5 volts and 2.3 volts. Anything higher than 2.50 volts will trigger the fault.
Could a wiring problem cause code 431 instead of a bad sender?
Yes. A short in the harness that lets battery voltage reach the signal wire can cause the same fault even if the sender itself tests normal. Always check wiring condition and connectors along with the sender.
Is there a reset procedure for code 431?
No reset procedure is listed for this code. Once the sender and wiring test within the expected resistance and voltage ranges, the fault condition should clear on its own.