The Manual Valve
The manual valve directs line pressure to the circuit the gear selector selects. It is connected mechanically to the gear selector by the shift cable. This connection is often adjustable. If incorrectly adjusted, the manual valve will leak line pressure into the wrong circuit.
The vehicle may creep when the transmission is in neutral. This drag causes damage and overheating of the transmission's clutch. Inspect the shift cable and linkage adjustment; adjust if necessary. This adjustment is a matter of safety. Refer to the manufacturer's manual and look for any TSBs before adjusting the linkage.