JLG Telehandler 33258 Fault Code: UGM Output Drivers - Transmission 1 Coil - Open Circuit
UGM Output Drivers - Transmission 1 Coil - Open Circuit · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault 33258 sets when the UGM (Universal Ground-based Module) detects an open circuit at output J1-7, the transmission 1 coil, on a machine configured for hydrostatic transmission. The controller deactivates the J1-7 output, holds the last valid gear selection, and flashes the gear selection symbol on the cab display. The fault latches until the machine is power cycled.
Medium severity. This is a machine system distress indicator, not an immediate catastrophic failure. The machine keeps running in its last valid gear, but transmission control is degraded until the open circuit is fixed and the machine is power cycled.
What does JLG Telehandler error code 33258 mean?
Fault code 33258 points to an open circuit detected by the UGM at output J1-7, which drives the transmission 1 coil. This only applies to machines where the transmission is configured as hydrostatic. When the UGM sees this output open, it cannot reliably command that coil, so it shuts the output down rather than let it behave unpredictably.
Once the fault sets, the UGM deactivates the J1-7 transmission 1 coil output, holds the transmission in whatever gear was last validly selected, and flashes the gear selection symbol on the LCD in the cab so the operator knows something is wrong with gear control.
The fault is a latching fault. It stays active until the machine is power cycled, even if the open circuit condition goes away on its own or is intermittent. That means a simple wiggle of a connector will not clear the code without a power cycle afterward.
What triggers a JLG Telehandler 33258 code?
The UGM sets this fault when the machine's transmission is configured as hydrostatic and the module detects an open circuit at output J1-7, the transmission 1 coil driver.
Common causes of 33258
- Open circuit in the wiring between the UGM output J1-7 and the transmission 1 coil
- Damaged, corroded, or disconnected connector at the transmission 1 coil or at the UGM J1 connector
- Failed or open transmission 1 coil winding
- Blown fuse or open circuit protection device feeding the J1-7 output circuit, if equipped
How to troubleshoot JLG Telehandler 33258: first checks
- Inspect the wiring harness between UGM connector J1, pin 7, and the transmission 1 coil for chafing, cuts, pinches, or disconnects
- Check the transmission 1 coil connector and the UGM J1 connector for corrosion, bent pins, or loose terminals
- Verify continuity through the transmission 1 coil winding itself with the connector disconnected
- Confirm the transmission configuration setting is correct for the machine, since this fault only applies when hydrostatic is configured
- Check for any fuse or circuit protection in the J1-7 feed circuit and confirm it has not opened
How the code clears
No separate clearing step is listed beyond fixing the open circuit. This fault latches until the machine is power cycled, so after repairing the wiring, connector, or coil, cycle machine power off and back on to clear the fault and restore normal transmission 1 coil output control.
Frequently asked questions
What does fault code 33258 mean on a JLG telehandler?
It means the UGM detected an open circuit at output J1-7, which drives the transmission 1 coil, on a machine configured with a hydrostatic transmission. The module shuts that output down and holds the last valid gear until the issue is fixed and the machine is power cycled.
Will the machine still drive with fault 33258 active?
The UGM maintains the last valid gear selection after this fault sets, so the machine keeps running in that gear. The gear selection symbol on the cab display will flash to alert the operator that gear control is affected.
How do I clear fault code 33258 after repair?
Fix the open circuit, whether it is in the wiring, connector, or the transmission 1 coil itself, then power cycle the machine. This fault latches until power is cycled, so it will not clear on its own even if the fault condition goes away temporarily.
Does fault 33258 apply to all JLG telehandler transmissions?
No. This fault only sets on machines where the transmission is configured as hydrostatic. If the transmission configuration is different, this specific open circuit check at output J1-7 does not apply.
What should I check first for an open transmission 1 coil circuit?
Start with the wiring and connectors between UGM output J1-7 and the transmission 1 coil, checking for corrosion, damage, or loose pins. Then check continuity through the coil winding itself with it disconnected from the harness.
Is fault code 33258 dangerous to keep operating with?
It is listed as a machine system distress indicator. The transmission holds its last valid gear rather than failing unpredictably, but you should diagnose and repair the open circuit as soon as practical rather than running indefinitely with degraded gear control.