Telehandler boom won't extend or lower: load moment cutout
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Applies to: JCB Loadall 535-550, JLG 644/1044 and other telehandlers
Symptoms
- Boom stops extending or lowering with an alarm
- Retract and raise still work
- Happens with lighter loads than it should
Why it happens
The load moment indicator cuts out functions that would tip the machine forward. A dirty or misadjusted sensor, or a fault in its wiring, can trip it falsely.
How to fix it
- Retract the boom to bring the load back in, then check the load chart.
- Check the machine is level and the frame-level indicator is centered.
- Clean and inspect the load sensor and wiring.
- Run the manual's LMI test and calibration.
Tools and parts
- Multimeter
- Contact cleaner
What the factory service manual covers
Load moment system: sensor test, calibration, wiring diagrams. The full procedure, specs and wiring diagrams are in the factory service manual for your machine.