Honda Acura NSX 1991 Service Manual page 424

Description
4. 4th Speed
The flow of fluid up to the l-2, 2-3 and 3-4 shift valves is the same as in the 3rd speed. When the speed of the
car reaches the prescribed value, the shift control solenoid valve A is turned OFF (Shift control solenoid valve B remains
OFF). As this takes place, the 3-4 shift valve is moved to the left side and uncovers the oil port leading to the 4th
clutch. Since the 1-2 and 2-3 shift valves are kept on the left side, the fluid flows through the 4th clutch; the power
is transmitted through the 4th clutch.
Fluid flows by way of:
-Line Pressure (4) + CPC Valve - Clutch Pressure Control (4') + l-2 Shift Valve - Clutch Pressure Control
Valve - 4th Clutch Pressure (40) --, 4th Clutch
The hydraulic pressure also flows to the 1st clutch. However no power is transmitted by means of the one-way
clutch as in 2nd and 3rd speed.
NOTE: When used, "left" or "right" indicates direction on the flow chart.
14-36