Bobcat T86 Lift Arm Position Sensor Fault Diagnostic

Symptoms

• Auto-level function cuts out unexpectedly during lift operations
• The lift control system triggers lift arm speed limits or warning codes
• Bucket tilt functions are choppy during boom lifting

Possible Causes

• Misaligned or loose physical rotary position rotary sensor link arm
• Moisture or pin corrosion in the boom frame electronic connector
• Internal failure or dead spot on the lift arm angle sensor potentiometer

Diagnostic Procedure

1. 1
   Inspect Mechanical Sensor Linkages

   Locate the rotary lift-arm position sensor mounted near the pivot join of the main mainframe. Inspect the mechanical bracket and linkage rods for bends, loose locknuts, or damage from trail branches or worksite materials.
2. 2
   Measure Sensor Electrical Supplies

   Unplug the position sensor harness connector. Turn the ignition on. Verify a steady 5.0V reference output on the reference pin, and test for a solid ground connection. If missing, look for a shared reference circuit failure.
3. 3
   Perform Voltage Sweep Output Verification

   Reconnect the sensor to the harness. Back-probe the signal return line with a multimeter. Slowly raise and lower the main lift arms using manual controls. The voltage signal should sweep smoothly from approximately 0.5V up to 4.5V without any sudden spikes or dropouts. If the voltage drops to zero during the sweep, replace the sensor.
4. 4
   Calibrate the Lift Arm Sensor

   Connect Bobcat Service Analyzer and navigate to the Calibration menu. Perform the Lift Arm Position Calibration procedure. Fully lower the arms to the frame stops, set the zero position, and then fully raise research parameters to complete sensor calibration.

Common Repairs

• Replacing the rotary lift arm cylinder position sensor
• Securing and aligning sensor links and brackets
• Running the lift arm and tilt position calibration procedure

Safety Precautions

• Always lower the lift arms flat onto the floor, shut down the engine, and engage mechanical arm lockout struts before working near the pivot joints.
• Ensure all technicians are clear of the loader's movement envelope during calibration.

Required Tools

• Digital Multimeter (DMM)
• Service Analyzer computer set
• Standard metric socket set

Related Fault Codes

People Also Ask

• How do you calibrate the lift arm position sensor on a Bobcat T86?
• What causes Bobcat fault code M0235?
• Why does my Bobcat T86 auto-level function stop working during a lift?
• Where is the lift arm position sensor located on a Bobcat T86 loader?
• How do I test the voltage of a Bobcat lift arm sensor harness?
• What is the procedure for resetting Bobcat code M0236?

Related Guides

Suggested Follow-Up Guides

• Bobcat T86 Hydraulic Valve Block Solenoid Replacement Guide
• How to Diagnose Bobcat 7-Pin Attachment Control Harness Faults
• Bobcat T86 Hydrostatic Drive Pump Calibration Procedure
• Troubleshooting Bobcat ACS (Advanced Control System) Actuators
• Bobcat T86 Main Controller (Gateway) Firmware Update and Diagnostic Guide

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