Valve spool will not return to center

A) Pilot drain plugged




B) Pilot valve stuck in one position



C) Return spring(s) weak or broken

A) Check internal or external drain ports for blockage. Check external drain line for kinks or collapsed line.

B) Check for solenoid burnout or seizure. Remove and clean pilot valve spool. Check pilot valve springs for proper tension.

C) Remove and replace.

Valve spool does not shift

A) Solenoid(s) failure




B) Low or no pilot pressure




C) Pilot valve spool sticking

A) Check if valve spool is stuck, blocking solenoid plunger. Ensure that line voltage is above solenoid's rating.

B) Check the pilot pressure source. Check and clean pilot orifices. Check for collapsed external pilot supply line.

C) Remove and clean pilot valve spool. Check for improper valve torque. Check for and remove burrs.