JLG Telehandler 33189 Fault Code: UGM Output Drivers - Main Telescope In Valve - Open Circuit
UGM Output Drivers - Main Telescope In Valve - Open Circuit · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault 33189 sets when the UGM (Universal Ground Module) detects an open circuit or a lost current feedback condition on output J2-34, which drives the main telescope in valve. The UGM shuts off that output and flags machine system distress. The fault latches until the machine is power cycled.
Medium severity. The machine loses telescope in function on that valve until the fault is cleared, but this is not an immediate safety-critical failure like a brake or lift interlock fault. Still, treat any lost function during lift work with caution and stop to diagnose.
What does JLG Telehandler error code 33189 mean?
This fault means the UGM (Universal Ground Module), which controls output drivers for various hydraulic valves, has detected a problem with the circuit feeding the main telescope in valve at output J2-34. Either the circuit is open (broken wire, bad connector, failed coil) or the UGM lost its current feedback signal, which it uses to confirm the valve is actually being driven.
When this happens, the UGM deactivates output J2-34 so the main telescope in valve will not operate, and it raises an indicator showing machine system distress. This is the controller's way of protecting itself and the machine from an unverified or failed output circuit.
The fault stays active, or latched, until the operator or technician cycles power to the machine. Simply fixing the wiring issue does not clear it on its own. A power cycle is required after the repair.
Common causes of 33189
- Open circuit in the wiring between the UGM output J2-34 and the main telescope in valve coil
- Failed or damaged main telescope in valve coil (open winding)
- Loose, corroded, or disconnected connector pins at the valve or along the harness run to J2-34
- Lost current feedback signal at the UGM, even if the circuit is not fully open, which the UGM treats as a possible fault condition
How to troubleshoot JLG Telehandler 33189: first checks
- Inspect the wiring harness from the UGM output J2-34 to the main telescope in valve for visible damage, chafing, or disconnection
- Check the connector at the main telescope in valve coil for corrosion, bent pins, or a loose fit
- Test continuity of the coil winding on the main telescope in valve to confirm it is not open
- Check the UGM connector at J2-34 for corrosion or a poor pin connection
- Verify ground and power connections related to the valve circuit are clean and tight
How the code clears
No separate clearing step beyond a power cycle is listed for this code. Once the open circuit or wiring problem is repaired, cycle power to the machine (shut it down and restart) to clear the latched fault. If the fault returns after the power cycle, the underlying wiring or valve issue has not been fully resolved.
Frequently asked questions
What does JLG fault code 33189 mean?
It means the UGM controller detected an open circuit or a lost current feedback condition on the output that drives the main telescope in valve, at output J2-34. The UGM disables that output and flags machine system distress.
Will the telescope function still work with fault 33189 active?
The main telescope in valve output is deactivated by the UGM when this fault is active, so telescope in movement on that circuit will not function until the fault is diagnosed and cleared.
How do I clear fault code 33189 on a JLG telehandler?
Repair the open circuit or wiring issue causing the fault, then power cycle the machine. The fault latches until power is cycled, so simply fixing the wiring will not clear it without a restart.
What usually causes this open circuit fault?
Common causes include a broken or disconnected wire between the UGM and the valve, a failed valve coil, corroded or loose connector pins, or a lost current feedback signal detected internally by the UGM.
Is fault code 33189 dangerous to keep operating with?
It is not listed as an immediate critical safety fault, but losing telescope in function during lift operations can create operational hazards. Stop and diagnose the issue rather than continuing to work around it.
Where is output J2-34 located?
J2-34 is the UGM output pin dedicated to the main telescope in valve. Checking the wiring and connector at this pin, along with the harness run to the valve coil, is the starting point for diagnosis.