Fault Phenomenon: Volvo G990 grader blade cannot enter float mode, remains rigid.

Troubleshooting Process:
– Checked control valve: mechanical spring for float position broken.
– Checked handle: handle travel normal.
– Checked spool: spool cannot reach float position.
– Checked oil path: no blockage.

Root Cause: The mechanical spring responsible for positioning or returning the float function inside the blade control valve is broken, preventing the spool from reaching the float zone.

Required Parts: Control valve spring repair kit.