JLG Scissor Lift 336 Fault Code: Crank Sync Noise
Also called Lift Dn Open Circuit
Crank Sync Noise · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Code 336 (SPN 636 / FMI 2) sets when the ground board does not detect current flow to the lift down solenoid during normal operation. It points to an open or high-resistance circuit in the lift down solenoid wiring or the solenoid itself.
Medium severity. The machine will likely lose lift down function until this is fixed, which limits normal operation but is not an immediate safety emergency by itself. Do not force lowering functions or bypass interlocks while troubleshooting.
What does JLG Scissor Lift error code 336 mean?
Fault code 336 on a JLG scissor lift means the ground board expected to see current flowing through the lift down solenoid circuit during normal operation, but did not detect it. This tells the controller the circuit is open somewhere between the ground board output and the solenoid coil.
The lift down solenoid controls the hydraulic valve that allows the platform to lower. The ground board sends a pulse-width-modulated (PWM) signal to power it, so if the circuit is broken, the platform may not lower properly on command.
This code is tied to the lift down function specifically. It does not necessarily affect lift up or drive functions, but any interruption in lowering control should be treated seriously since it affects safe platform operation.
Common causes of 336
- Open or broken wiring in the lift down solenoid circuit between ground board J1-26 (power/PWM) and J1-27 (ground)
- Failed or damaged lift down solenoid coil (resistance should measure about 20 ohms)
- Corroded, loose, or damaged connectors in the lift down solenoid circuit
- Faulty ground board that is not driving the circuit properly
How to troubleshoot JLG Scissor Lift 336: first checks
- Check continuity through the entire lift down solenoid circuit, from the ground board connector to the solenoid and back
- Measure resistance across the lift down solenoid coil, it should read about 20 ohms; a reading far outside this suggests a bad coil
- Inspect all wiring in the circuit for physical damage such as chafing, cuts, or pinched sections
- Inspect connectors at the ground board (J1-26 and J1-27) and at the solenoid for corrosion, looseness, or pin damage
How the code clears
No reset procedure is listed for this code. Once the open circuit is found and repaired, whether that means fixing wiring, replacing the solenoid, or replacing the ground board, the fault should clear on its own during normal operation checks. If it does not clear after repair, recheck continuity through the full circuit before assuming the ground board is bad.
Frequently asked questions
What does JLG fault code 336 mean?
It means the ground board did not detect current flow to the lift down solenoid during normal operation, indicating an open circuit somewhere in that wiring path or in the solenoid itself.
Will fault code 336 stop the scissor lift from working?
It can affect the lift down function specifically, since that circuit is not confirmed to be carrying current. Other functions may still work, but lowering the platform on command may be unreliable or not work at all.
What resistance should the lift down solenoid read?
The lift down solenoid should measure about 20 ohms. A reading well above or below this points to a failed coil rather than a wiring problem.
Where does the lift down solenoid get its signal from?
The ground board powers the lift down solenoid with a PWM signal from J1-26, and the solenoid grounds back to the ground board at J1-27. Checking continuity and connections at both points is part of diagnosing this code.
Is fault code 336 the same as replacing the ground board right away?
No. The recommended steps are to check circuit continuity, inspect wiring for damage, and only replace the ground board if those checks do not resolve the fault.
Is there a specific reset procedure for code 336?
No reset procedure is listed for this code. Repairing the open circuit or faulty component should allow the fault to clear during normal operation.