JLG Telehandler 33186 Fault Code: UGM Output Drivers - Main Telescope Out Valve - Open Circuit
Also called Telescope Out Valve - Open Circuit
UGM Output Drivers - Main Telescope Out Valve - Open Circuit · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault 33186 means the JLG UGM (upper/universal ground module) has detected an open circuit on output J2-35, the main telescope out valve driver, or lost current feedback on that circuit. The controller shuts down the telescope out output and latches the fault until a power cycle. It signals machine system distress and points at wiring, the valve coil, or the connector, not a software problem.
Medium severity. The machine is not damaged by this fault, but telescope out function is disabled until the open circuit is fixed and power is cycled. Treat it as a stop-and-diagnose issue if telescope function is needed for the job, since operating with a dead telescope out circuit can be a functional safety issue on a job site depending on the task.
What does JLG Telehandler error code 33186 mean?
Fault code 33186 is set by the UGM (the machine's ground-side control module) when it detects an open circuit at output J2-35, which drives the main telescope out valve. It can also be triggered when the UGM detects a current feedback lost condition on that same output circuit and flags it internally as the likely cause of the fault.
When this happens, the controller responds by deactivating the main telescope out valve output entirely. This is a protective action: rather than let the valve driver behave unpredictably with an open circuit, the module cuts power to that output until the fault is cleared.
The listed indicator is simply 'machine system distress,' meaning the operator will see a general fault indication rather than a function-specific message. The underlying issue is electrical: something in the telescope out valve circuit, from the UGM output pin through the wiring harness to the valve coil, is not completing the circuit the way the module expects.
What triggers a JLG Telehandler 33186 code?
The UGM sets this fault when it detects an open circuit at output J2-35 (main telescope out valve) or when it detects a current feedback lost condition on that output and its internal logic flags this fault as the cause.
Common causes of 33186
- Open circuit in the wiring between the UGM output J2-35 and the main telescope out valve coil
- Loose, corroded, or damaged connector pins in the telescope out valve circuit
- Failed or open valve coil on the main telescope out solenoid
- Damaged or disconnected wiring at pin J1-9 on the ground module, which is specifically called out for this fault
- Internal UGM output driver failure on the J2-35 circuit (less common, but possible if wiring and valve check out)
How to troubleshoot JLG Telehandler 33186: first checks
- Inspect the wiring harness and connectors between the UGM (J2-35) and the main telescope out valve for breaks, chafing, or corrosion
- Check the connector and pin J1-9 on the ground module specifically, since this pin is identified as the wiring point to verify for this fault
- With power off, check continuity of the telescope out valve coil and its wiring back to the module, looking for an open circuit rather than a short
- Inspect connectors at both ends of the circuit for backed-out pins, moisture intrusion, or corrosion that could cause an intermittent or full open circuit
- After repairs, cycle power to the machine since this fault is latched and will not clear on its own
How the code clears
This fault latches and stays active until the machine's power is cycled. There is no separate software reset procedure listed beyond fixing the open circuit and power cycling the machine controller. If the underlying wiring or valve problem is not corrected, the fault will likely reset again as soon as the UGM tries to drive the telescope out valve.
Frequently asked questions
What does JLG fault code 33186 mean?
It means the machine's UGM has detected an open circuit, or a lost current feedback condition, on the output that drives the main telescope out valve (J2-35). The module disables that output until the issue is fixed and power is cycled.
Why won't my telehandler telescope out after this fault?
Because the UGM deactivates the main telescope out valve output as soon as it detects the open circuit or current feedback loss. Telescope out will not work again until the circuit is repaired and the machine's power has been cycled.
Where should I check wiring first for code 33186?
Start at pin J1-9 on the ground module, since that connection point is specifically identified as part of this circuit. From there, trace the wiring out to the main telescope out valve coil, checking connectors and pins along the way.
Will restarting the machine clear fault 33186?
The fault is latched until a power cycle, so cycling power is required. However, if the open circuit itself is not repaired, the fault will likely reappear the next time the telescope out valve is commanded.
Is fault code 33186 a valve problem or a wiring problem?
It can be either. The UGM only knows it has an open circuit or lost current feedback on that output; it does not distinguish between a bad wire, a bad connector, or a failed valve coil. All three need to be checked.
Is it safe to keep operating the telehandler with this fault active?
The main telescope out function will be disabled, so you will lose that movement capability. Since this affects machine function during lifting and material handling work, it should be diagnosed and repaired before relying on the machine for jobs that need telescope out travel.