JLG Telehandler 33198 Fault Code: UGM Output Drivers - Auxiliary Function - A Valve - Short to Ground
UGM Output Drivers - Auxiliary Function - A Valve - Short to Ground · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault 33198 is set by the UGM (a JLG control module) when it detects a short to ground on the auxiliary function-A valve output at J2-9, or when it loses current feedback on the aux return circuit at J3-14. The machine responds by shutting down auxiliary function-A and function-B and disabling continuous auxiliary hydraulics. It shows as a machine system distress indicator and stays latched until the machine is power cycled.
Medium severity. This code does not stop the machine from driving or lifting on its own, but it disables both auxiliary hydraulic functions and the continuous auxiliary hydraulics feature. Any attachment or tool run through the auxiliary circuit, such as a grapple, auger, or sweeper, will lose function until the fault is diagnosed and cleared.
What does JLG Telehandler error code 33198 mean?
Fault 33198 comes from the UGM, JLG's control module that manages machine outputs including auxiliary hydraulic valves. This specific code is tied to the auxiliary function-A valve output, wired through connector point J2-9, and the current feedback return path at J3-14 which is shared between auxiliary function-A and function-B.
When the UGM senses that the function-A valve output is shorted to ground, or when it loses the current feedback signal it expects back from that circuit, it sets an internal flag and logs fault 33198. Because the module cannot always tell immediately whether the short or the lost feedback is the true cause, it treats both conditions as triggers for this single code.
To protect the wiring and valve coil from damage, the UGM deactivates the function-A valve output, disables the current feedback input (which also takes function-B out of service since they share the return), shuts off continuous auxiliary hydraulics, and turns off the continuous auxiliary hydraulics indicator. This is a protective shutdown, not a nuisance fault.
Common causes of 33198
- A short to ground somewhere in the wiring between the UGM output at J2-9 and the auxiliary function-A valve coil
- A damaged or shorted auxiliary function-A valve coil itself
- A broken, corroded, or disconnected connection in the current feedback return circuit at J3-14, causing the UGM to see a lost feedback condition
- Chafed or pinched harness wiring in the auxiliary hydraulic circuit that allows the output or return wire to contact machine ground
How to troubleshoot JLG Telehandler 33198: first checks
- Inspect the wiring harness between the UGM connector J2-9 and the function-A valve coil for chafing, cuts, or pinch points that could cause a short to ground
- Check the current feedback return wiring at J3-14 for loose, corroded, or disconnected pins, since a lost feedback signal on this circuit will also set this code
- Test the auxiliary function-A valve coil resistance and check for continuity to ground on the coil and its wiring
- Look at connector pins at both the UGM and the valve for corrosion, bent pins, or moisture intrusion, all common causes of intermittent shorts and feedback loss
- Confirm the fault is current and not just historical by attempting to power cycle the machine and re-checking for the active fault before doing extended wiring work
How the code clears
This fault latches until the machine is power cycled. No separate reset procedure is listed for this code, so after repairing the wiring, connector, or valve coil issue, cycle machine power off and back on and confirm the fault does not re-set and that auxiliary function-A and function-B, along with continuous auxiliary hydraulics, return to normal operation.
Frequently asked questions
What does JLG fault code 33198 mean?
It means the UGM control module detected a short to ground on the auxiliary function-A valve output, or lost the current feedback signal on the shared aux return circuit. Either condition sets this same code.
Will fault 33198 stop my telehandler from driving?
No. This fault affects the auxiliary hydraulic function-A and function-B outputs and the continuous auxiliary hydraulics feature. It does not directly disable driving, steering, or lifting functions.
Why did both auxiliary function-A and function-B stop working?
Function-A and function-B share the same current feedback return circuit at J3-14. When the UGM disables that feedback input in response to the fault, both auxiliary functions go offline together, even though the fault is specific to function-A's valve output.
How do I clear fault code 33198 after fixing the problem?
Power cycle the machine. This fault is latched until a power cycle, and no separate reset procedure is documented. If the underlying short or feedback issue is truly fixed, the fault should not return after the power cycle.
What is the most likely cause of this fault?
The most common causes are a chafed or pinched wire that shorts the function-A output to ground, a failed valve coil, or a bad connection in the current feedback return circuit. All three should be checked before assuming a control module problem.
Can I keep operating the machine with this fault active?
You can generally continue basic operation since driving and lifting are not disabled, but any attachment relying on auxiliary function-A, function-B, or continuous auxiliary hydraulics will not work until the fault is resolved. Treat any hydraulic short to ground as worth prompt attention to avoid further wiring or valve damage.