JLG Telescopic Boom Lift 85 Fault Code: Reference Voltage 4
Also called Problems with the Moment or Load Pin System
Reference Voltage 4 · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 85 (SPN/FMI 2) on JLG telescopic boom lifts flags problems with the Moment or Load Pin System, and can also indicate Reference Voltage 4 is outside its permissible range. It covers out-of-range force readings, sensor fault flags, mismatched pin detection, or a bad actuator reference voltage supply.
High severity. This code affects the load/moment monitoring system that helps prevent overload and tip-over conditions. Until it's diagnosed and cleared, treat load capacity indications on the machine as unreliable and follow manual load charts and visual judgment carefully.
What does JLG Telescopic Boom Lift error code 85 mean?
Fault code 85 is tied to two related descriptions: 'Problems with the Moment or Load Pin System' and 'Reference Voltage 4'. The moment pin and load pin are sensors that measure the horizontal and vertical forces acting on the boom structure so the machine's control system can judge whether it's approaching an overload or moment (tip-over) condition.
When this code sets, the control unit has detected that force readings from one of these pins are out of the allowed range, that a pin has reported an internal fault flag, that a different pin than the one used during calibration has been detected, or that the reference voltage supplying the sensor circuit (listed as an auxiliary value of 5 volts) is outside its permissible range.
Because this system is directly tied to load and moment protection, a fault here means the machine may not be able to properly warn the operator of an overload or stability risk.
Common causes of 85
- Moment pin horizontal or vertical force reading out of the allowed range
- Load pin horizontal or vertical force reading out of the allowed range
- Moment pin sensor reporting an internal fault flag
- Load pin sensor reporting an internal fault flag
- A moment pin detected on the system that is different from the one used to calibrate the machine
- A load pin detected on the system that is different from the one used to calibrate the machine
- Reference voltage for the actuator (auxiliary value 5 volts) not within the permissible range, which is classified as a control unit hardware fault
How to troubleshoot JLG Telescopic Boom Lift 85: first checks
- Check the voltage supply to the moment/load pin sensor circuit and confirm it is in the permissible range around the 5 volt reference
- Cycle the ignition off and back on, then recheck whether the fault is still present
- Inspect moment pin and load pin wiring and connectors for corrosion, damage, or loose pins
- Confirm that the moment pin and load pin currently installed match the ones used during the machine's original calibration
- Check for visible damage or overload conditions that could explain out-of-range horizontal or vertical force readings
How the code clears
The fault message is noted to disappear once the reference voltage returns to the normal range on its own. Beyond that, the listed help steps are to check the voltage supply, switch the ignition off and on again, and check again. No separate reset procedure beyond these steps is listed for this code.
Frequently asked questions
What does JLG fault code 85 mean?
It means the control system has detected a problem with the moment pin or load pin system, or with Reference Voltage 4 that supplies those sensors. This can include out-of-range force readings, a sensor fault flag, a mismatched pin, or an actuator reference voltage outside the permissible range.
Is fault code 85 safe to keep operating with?
No. This fault touches the system that monitors load and moment (tip-over) forces on the boom. Until it's diagnosed, don't rely on the machine's load protection system and follow manual load charts and standard safe-operating judgment.
Will cycling the ignition clear fault code 85?
It might, if the underlying cause was a temporary out-of-range voltage condition. The listed help steps are to check the voltage supply, switch the ignition off and on again, and check again. If the fault returns, further inspection of the pin sensors and wiring is needed.
Why would a 'new pin detected' fault trigger code 85?
The control system stores calibration data tied to the specific moment pin or load pin installed when the machine was last calibrated. If a different pin is detected, whether from a replacement or wiring change, the system flags it because the stored calibration may no longer match.
What is Reference Voltage 4 on this machine?
It's listed as the reference voltage supplying an actuator in the moment/load pin circuit, with an auxiliary value of 5 volts. When this voltage falls outside its permissible range, the control unit logs it as a hardware fault.
Does fault code 85 point to a sensor problem or a wiring problem?
It can be either. The causes listed include out-of-range force readings and sensor fault flags from the pins themselves, as well as a reference voltage supply issue, which points toward wiring, connectors, or the control unit hardware rather than the pin sensor alone.