JLG Scissor Lift 84 Fault Code: LSS Cell #4 Error
Also called Indicates Problem with the Platform Load Sensing System - LSS Cell #4 Error, Reference Voltage 2
LSS Cell #4 Error · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 84 (SPN / FMI 2) flags a problem with Load Sensing System (LSS) cell #4, or a reference voltage fault on a control unit actuator circuit. JLG reports it when cell #4's bridge reads <2Vdc or >3Vdc, when the LSS module can't read cell #4's internal memory, or when the LSS status message reports a cell 4 error while the machine's load setup is set to CUTOUT PLT or CUTOUT ALL. It's treated as priority 11.
High severity. The system may cut out platform function or all machine function depending on setup, and the controller may treat the machine as overloaded even if it isn't. Don't bypass the LSS to keep working; get it diagnosed before resuming lift operations.
What does JLG Scissor Lift error code 84 mean?
This code relates to the Load Sensing System (LSS), which JLG uses to monitor platform load through load cells, including cell #4. If the LSS can't get a valid, stable reading from cell #4, it can't confirm whether the platform is safely loaded, so it flags an error and, depending on setup, may cut out platform function or the entire machine.
A second body of text ties this same code to a control unit reference voltage fault, described as a 5 volt auxiliary value used to feed an actuator circuit. If that reference voltage drifts out of its permissible range, the control unit can't trust readings tied to it, which includes load cell circuits like LSS cell #4.
In short, code 84 means the load sensing system has lost confidence in cell #4's data, either because of a wiring/sensor problem at the cell or because the reference voltage supplying the sensing circuit is out of range.
What triggers a JLG Scissor Lift 84 code?
The fault sets when cell #4's bridge voltage reads <2Vdc or >3Vdc, or when the LSS module cannot read cell #4's internal memory. It also sets when the LSS status message (0x81) reports a 'cell 4 error' while the machine setup's load response is configured to 1=CUTOUT PLT or 2=CUTOUT ALL. Separately, a reference voltage fault can trigger when the 5V auxiliary supply for an actuator circuit falls outside its permissible range; this version of the fault clears itself once the voltage returns to normal range.
Common causes of 84
- Cell #4's bridge voltage reading below 2Vdc or above 3Vdc
- LSS module unable to read cell #4's internal memory
- LSS status message reporting a cell 4 error while load setup is set to CUTOUT PLT or CUTOUT ALL
- Sensor for cell #4 unplugged or damaged
- Machine assumed to be overloaded by the control logic
- Control unit reference voltage (5V auxiliary) for an actuator circuit out of the permissible range
How to troubleshoot JLG Scissor Lift 84: first checks
- Inspect the connector and wiring at LSS cell #4 for being unplugged, loose, corroded, or physically damaged
- Check the reference voltage supply feeding the LSS actuator circuit; it should sit in its normal range around the 5V auxiliary value
- Cycle the ignition off and on again, then recheck whether the fault is still active, since the reference voltage version of this fault clears once voltage returns to normal range
- Check the machine's load setup configuration (CUTOUT PLT or CUTOUT ALL) to understand how the fault is affecting machine function
- Look for damage to cell #4 itself if wiring and connectors check out fine
How the code clears
For the reference voltage version of this fault, it is described as a fault message that disappears once the voltage returns to the normal range; switching the ignition off and on again and rechecking is the listed step. No separate clearing step is listed for the LSS cell #4 error itself beyond fixing the sensor, wiring, or connection issue causing it.
Frequently asked questions
What does JLG fault code 84 mean?
It means the Load Sensing System has detected a problem with cell #4, either a bridge voltage reading out of range, a memory read failure, or a status message reporting a cell 4 error, or it means a control unit reference voltage for an actuator circuit is out of its permissible range.
Can I keep operating the scissor lift with code 84 active?
You shouldn't. Depending on the machine's load setup, this fault can cut out platform function or the entire machine, and it may falsely indicate an overload condition. Get it diagnosed before resuming lift operations.
Will cycling the ignition clear fault code 84?
It might clear the reference voltage version of this fault if the voltage has returned to its normal range, since that fault message disappears on its own once voltage is normal. Switch the ignition off and on, then recheck. If it's a cell #4 sensor or wiring issue, cycling power alone won't fix it.
What's the most common cause of an LSS cell #4 error?
JLG's guidance points to the sensor for cell #4 being unplugged or damaged as the likely cause when this error shows up.
Is fault code 84 a serious problem?
It's rated priority 11 and directly affects the load sensing system, which is a safety-related system on the scissor lift. It should be treated as a stop-and-diagnose issue, not something to ignore.
Does the machine's load cutout setting affect how code 84 behaves?
Yes. If the machine setup's load response is set to CUTOUT PLT or CUTOUT ALL, a reported cell 4 error will cause the corresponding cutout behavior, either cutting out platform function or all machine function.