Reverse Inhibitor Control

While the vehicle is moving forward, the PCM keeps shift solenoid valve E OFF. Shift valve E covers the port of line pressure (3') leading to the servo valve reverse position. The servo valve cannot be shifted to reverse position, and hydraulic pressure is not applied to the 4th clutch from servo valve for reverse. As a result, power is not transmitted in the reverse direction.

Fig 1: Identifying Hydraulic Flow - R Position: Driving In Reverse Gear

Courtesy of AMERICAN HONDA MOTOR CO., INC.