Fault Phenomenon: Komatsu GD655 grader transmission shift logic is erratic, instrument shows speed jumping.

Troubleshooting Process:
– Remove sensor: sensor magnetic tip covered in metal filings.
– Checked oil sample: abnormal wear particles in transmission oil.
– Checked signal: debris interfering with magnetic induction signal.
– Checked gear: signal gear intact.

Root Cause: Metal debris from early internal transmission wear was attracted to the speed sensor’s magnet, causing signal pulse loss or error.

Required Parts: Clean sensor, replace transmission oil and filter, locate wear source.