JLG Telehandler 33370 Fault Code: UGM Output Drivers - Boom Float Valve - Short to Battery or Open Circuit
UGM Output Drivers - Boom Float Valve - Short to Battery or Open Circuit · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault 33370 sets when the boom ride/boom float module detects a short to battery or open circuit at the boom float valve output. It shows as machine system distress and shuts down boom float, boom ride, and the main lift up valve until the machine is power cycled.
Medium severity. The fault does not stop the machine from driving or lifting normally, but it disables boom float, boom ride, and the main lift up valve, which limits productivity and signals a wiring or valve problem that needs attention before those features are needed again.
What does JLG Telehandler error code 33370 mean?
Fault code 33370 is set by the UGM (the machine's control module handling boom ride/boom float functions) when it detects a short to battery or an open circuit at the boom float valve output driver. This is an output circuit fault, meaning the controller sent a command to the valve but the electrical feedback it saw back did not match what a healthy circuit should look like.
When this happens, the controller treats it as a system distress condition. It responds by locking out three related functions: the boom float feature, the boom ride feature, and the J2-11 main lift up valve. These are disabled and inhibited as a protective measure so the machine does not attempt to run a valve circuit that is electrically compromised.
The fault is described as an indicator-level condition, meaning it flags a real electrical problem at that output that needs to be found and fixed rather than something that will resolve itself. It stays active, latched, until the machine is power cycled.
What triggers a JLG Telehandler 33370 code?
The fault sets when the boom float feature is configured on the machine and the boom ride/boom float module detects either a short to battery or an open circuit at the boom float valve output.
Common causes of 33370
- A wiring short to battery voltage in the harness feeding the boom float valve output, causing the output driver to see voltage it did not command.
- An open circuit in the wiring or connector to the boom float valve, such as a broken wire, disconnected connector, or corroded terminal.
- A failed boom float valve coil that no longer presents a normal electrical load to the output driver.
- A failure inside the boom ride/boom float module's output driver circuit itself.
How to troubleshoot JLG Telehandler 33370: first checks
- Inspect the wiring harness and connectors between the UGM/boom ride module and the boom float valve for chafing, pinched wires, corrosion, or loose pins.
- Check the boom float valve connector for a solid, clean connection and confirm the coil is intact rather than open or shorted.
- Verify the boom float feature is properly configured for the machine, since the fault only sets when boom float is configured.
- With power off, check continuity of the wiring from the module output to the valve coil to rule out an open circuit before reapplying power.
- Look for any signs of a short to battery, such as damaged insulation where the float valve wiring runs near a constant power source.
How the code clears
This fault latches until the machine is power cycled. No separate clearing step is listed beyond turning the machine off and back on after the underlying wiring or valve issue is repaired. If the short or open circuit is still present after the power cycle, the fault will set again the next time the boom float feature is used.
Frequently asked questions
What does JLG fault code 33370 mean?
It means the boom ride/boom float module detected a short to battery or an open circuit at the boom float valve output. The controller responds by disabling boom float, boom ride, and the main lift up valve.
Will fault code 33370 stop my telehandler from driving?
No. This fault affects the boom float valve output circuit and related lift functions. It does not directly disable driving, but it inhibits the main lift up valve, boom float, and boom ride until it is resolved.
How do I clear fault 33370?
The fault latches until the machine is power cycled. There is no separate clearing procedure listed beyond fixing the wiring or valve problem and cycling power.
Why did the main lift up valve get disabled by a boom float fault?
The J2-11 main lift up valve is inhibited as one of the protective actions the controller takes when it detects a short to battery or open circuit at the boom float valve output, even though the fault is centered on the float valve circuit.
Does this fault only happen if boom float is turned on?
Yes. The fault only sets if the boom float feature is configured on the machine and the module detects the short or open circuit condition at that output.
What should I check first for fault 33370?
Start with the wiring and connectors between the control module and the boom float valve, checking for shorts to battery voltage, open wires, corrosion, or a failed valve coil.