JLG Telehandler 33371 Fault Code: UGM Output Drivers - Boom Tank Valve - Short to Battery or Open Circuit
UGM Output Drivers - Boom Tank Valve - Short to Battery or Open Circuit · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault 33371 sets when the boom ride/boom float module detects a short to battery or an open circuit at the boom tank valve output. If boom ride or boom float is configured on the machine, the controller disables those features and inhibits the main lift up valve at J2-11 until the machine is power cycled.
High severity. The fault does not necessarily stop the machine from working, but it disables boom ride, boom float, and inhibits the main lift up valve function, which affects boom control and operator comfort features. Treat it as a stop-soon condition since lift function is impacted.
What does JLG Telehandler error code 33371 mean?
Fault code 33371 relates to the UGM (a control module handling output drivers) and specifically the boom tank valve output. This valve is part of the boom ride and boom float system, which allows the boom to float or absorb ride motion under certain hydraulic control conditions.
When the boom ride/boom float module detects that this output circuit is either shorted to battery voltage or has gone open circuit, it flags fault 33371 and takes protective action. This means the system is not getting the expected electrical signal back from the valve circuit, so it cannot trust the valve to work correctly.
Because this valve interacts with the main lift up function, the controller also inhibits the main lift up valve at connector location J2-11 as a precaution, along with turning off boom ride and boom float entirely until the fault is cleared by a power cycle.
What triggers a JLG Telehandler 33371 code?
The fault sets if the boom ride or boom float feature is configured on the machine and the boom ride/boom float module detects a short to battery or an open circuit at the boom tank valve output.
Common causes of 33371
- Wiring harness fault on the boom tank valve output circuit causing a short to battery voltage
- Open circuit in the wiring between the module and the boom tank valve, such as a broken wire or disconnected connector
- Failed or damaged boom tank valve coil with an open or shorted winding
- Corroded, loose, or damaged connector pins on the boom tank valve or its harness connector
- Internal fault in the boom ride/boom float module's output driver for this circuit
How to troubleshoot JLG Telehandler 33371: first checks
- Confirm whether boom ride or boom float is configured on this machine, since the fault only sets when one of these features is active
- Inspect the wiring harness and connectors at the boom tank valve for visible damage, chafing, corrosion, or loose pins
- Check the boom tank valve coil resistance and continuity to rule out an open or shorted coil
- Verify the connector at J2-11 and related main lift up valve wiring for damage, since this valve is inhibited by the fault
- Look for pinched, cut, or rubbed wiring along the boom tank valve circuit route, especially near moving boom sections
- Check for any signs of a direct short to battery voltage on the boom tank valve output wire, such as melted insulation or heat damage
How the code clears
This fault latches until the machine is power cycled. After repairing the wiring, connector, valve coil, or module issue, cycle the machine's power off and back on to clear the fault and restore boom ride, boom float, and the main lift up valve function. No separate clearing step is listed beyond the power cycle.
Frequently asked questions
What does JLG fault code 33371 mean?
It means the boom ride/boom float module detected a short to battery or an open circuit at the boom tank valve output. This disables boom ride, boom float, and inhibits the main lift up valve at J2-11 until the machine is power cycled.
Will fault 33371 stop my telehandler from lifting?
The main lift up valve function tied to J2-11 is inhibited by this fault, which affects boom lifting capability. Boom ride and boom float are also disabled. This is a functional loss that should be diagnosed and repaired promptly.
How do I clear fault code 33371 on a JLG telehandler?
The fault latches until the machine is power cycled. Repair the underlying wiring, connector, valve, or module issue first, then power cycle the machine to clear the fault.
Does this fault only happen if boom ride or boom float is installed?
Yes. The fault only sets if the boom ride or boom float feature is configured on the machine. Machines without these features configured will not trigger this fault.
What is the boom tank valve and why does it matter?
The boom tank valve is an output controlled by the boom ride/boom float module. It plays a role in the boom ride and boom float functions, which affect how the boom responds to hydraulic pressure changes during operation.
What should a technician check first for code 33371?
Start by confirming whether boom ride or boom float is configured, then inspect the wiring and connectors at the boom tank valve output and check the valve coil for open or short conditions before checking the J2-11 wiring for the main lift up valve.
Can a bad connector cause fault 33371?
Yes. Corroded, loose, or damaged connector pins at the boom tank valve or its harness can create an open circuit or intermittent short condition that triggers this fault.