JLG Telehandler 33190 Fault Code: UGM Output Drivers - Main Telescope In Valve - Short to Ground
UGM Output Drivers - Main Telescope In Valve - Short to Ground · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Code 33190 sets when the UGM (Universal Guidance Module, the telehandler's main control module) detects a short to ground at the main telescope in valve output (J2-34), or detects a lost current feedback condition on the telescope return input (J3-4). The machine flags this as system distress, disables the telescope in valve output, and disables both telescope in and telescope out function until the controller is power cycled.
High severity. This code disables telescope in and telescope out function entirely, which stops boom extension and retraction work. It is not an immediate engine or safety-damage event, but the machine cannot do its job until the fault is cleared, and a short to ground on a valve output circuit can indicate wiring or valve coil damage that will keep recurring until repaired.
What does JLG Telehandler error code 33190 mean?
Fault 33190 points at the output driver circuit for the main telescope in valve, controlled through the UGM at output J2-34. This valve controls boom telescope in movement on the hydraulic circuit.
When the UGM detects that this output has shorted to ground, or when it loses current feedback on the telescope return input at J3-4, it treats this as a system distress condition. To protect the output driver and wiring, the controller deactivates the J2-34 output and disables the current feedback input, which shuts down both telescope in and telescope out movement, since the feedback circuit is shared between them.
This is a latching fault. Once it sets, it stays active until the machine's power is cycled, even if the short or feedback loss is intermittent or clears on its own.
What triggers a JLG Telehandler 33190 code?
The UGM sets this fault when it detects either a short to ground at the main telescope in valve output (J2-34), or a current feedback lost condition on the telescope return input (J3-4). The controller sets an internal flag to determine whether this condition is the actual cause of the fault.
Common causes of 33190
- A short to ground in the wiring harness feeding the main telescope in valve coil, from chafed insulation, pinched wiring, or water intrusion at a connector.
- A failed or shorted valve coil on the main telescope in valve itself.
- A damaged or corroded connector at J2-34 or J3-4 allowing a ground path to form.
- An internal fault in the current feedback circuit for the telescope return input (J3-4), causing the UGM to see a lost feedback signal even without an actual valve fault.
- A UGM output driver failure on the channel controlling this valve.
How to troubleshoot JLG Telehandler 33190: first checks
- Inspect the wiring harness from the UGM to the main telescope in valve for chafing, pinched sections, or exposed conductors that could touch a grounded surface.
- Check the valve coil connector and the J2-34 and J3-4 connectors at the UGM for corrosion, moisture, bent pins, or loose terminals.
- Disconnect the main telescope in valve coil and check it for a short to ground using a meter with the machine powered down, comparing readings against a known-good coil if available.
- Trace the current feedback wiring for the telescope return input (J3-4) for damage or a poor connection, since a wiring fault there can trigger this code even if the valve itself is fine.
- Check for pinched or trapped wiring near boom pivot points or cable carriers, where repeated boom movement can eventually wear through insulation.
How the code clears
This fault latches until the machine's power is cycled. After making a repair, cycle machine power off and back on to attempt to clear the code. No separate reset procedure is listed for this code beyond the power cycle. If the underlying short or feedback loss condition is still present, the fault will set again as soon as the UGM re-tests the circuit.
Frequently asked questions
What does JLG fault code 33190 mean?
It means the UGM, the machine's main control module, detected a short to ground at the main telescope in valve output, or lost current feedback on the telescope return circuit. The controller disables telescope in and telescope out movement in response.
Why does code 33190 disable both telescope in and telescope out?
Because the current feedback input at J3-4 is shared between the telescope in and out functions. When the UGM decouples that feedback input to protect the circuit, both directions of telescope movement are disabled, not just the in direction.
Will cycling the key clear fault code 33190?
It can clear the latched fault, but only if the actual short to ground or feedback fault has been repaired first. If the wiring or valve issue is still present, the fault will return the next time the UGM checks the circuit.
Can I keep operating the telehandler with code 33190 active?
You will not be able to telescope the boom in or out at all once this fault sets, since the controller disables that function as a protective measure. Continued operation with a shorted output circuit also risks further wiring or valve damage, so repair before resuming full duty.
What parts should I check first for code 33190?
Start with the wiring harness and connectors between the UGM and the main telescope in valve, particularly at connections J2-34 and J3-4, and check the telescope in valve coil for an internal short to ground.
Is code 33190 an electrical or hydraulic problem?
It is rooted in the electrical control circuit for a hydraulic valve. The fault itself is detected in the wiring and output driver, but it directly affects hydraulic telescope function, so both systems are worth inspecting.