Bobcat S650 Hydraulics Locked Out, Lift Arm Bypass Warning
Fault Codes & Symptoms
Hydraulic controls are locked out. Related symptoms: - Hydraulics will not enable. - Error or fault code related to lift arm position. - Inability to calibrate lift arm position sensor. The machine starts, but the lift and tilt functions do not work. A warning light is on showing the lift arm bypass.
Confirmed cause: Defective lift arm position sensor. The internal wiper or resistive track had failed, causing erratic and illogical voltage signals back to the BICS controller. Repair performed: Replaced the lift arm position sensor. After installation, calibrated the new sensor using the machine's deluxe instrumentation panel or a dealer service tool, following the manufacturer's procedure. Verification: After sensor replacement and calibration, started the machine. The lift arm bypass warning light extinguished. Pressing the "PRESS TO OPERATE" button successfully enabled the hydraulic system. Lift and tilt functions operated normally through their full range of motion. Technician notes: - The lift arm position sensor can sometimes be damaged by debris or high-pressure washing. - Calibration is a required step after replacement. Failure to calibrate will result in continued faults or improper machine operation. - This fault prevents the operator from using the hydraulic controls but allows the engine to run, which can be confusing. The key is the specific warning light displayed.