Servo Apply Valve

SERVO APPLY VALVE





The servo apply valve, located in the valve body, is used to control reverse apply oil to the forward/reverse servo piston. When reverse is selected, the manual valve will allow oil to be applied to the servo apply valve. If vehicle speed input to the PCM indicates the vehicle is less than 8 km/h (5 mph) then the dog clutch can be moved to the reverse direction without causing damage. With the vehicle speed less than 8 km/h (5 mph), and reverse selected, the PCM will command high-line pressure. When high-line pressure is commanded, the pressure will move the servo apply valve against the spring which opens up the passage allowing oil to pass through the servo apply valve to the forward/reverse servo piston.
If reverse is selected when vehicle speed is greater than 8 km (5 mph), the PCM will command low-line pressure causing the servo apply spring to keep the passage in the servo apply valve closed, preventing oil to reach the forward/reverse servo piston. This action does not allow the dog clutch to move, thus preventing internal damage to the transaxle.