Honda Acura NSX 1991 Service Manual page 430

Description
Half Lock-up
Lock-up Control Solenoid Valve A: ON
The modulator pressure is released by the solenoid valve B, causing the modulator pressure in the left cavity of the lock-
up control valve to lower.
Also the modulator pressure in the left cavity of the lock-up timing valve B is low. However the throttle B pressure is
still low at this time, consequently the lock-up timing valve B is kept on the right side by the spring force.
With the lock-up control solenoid valve B turned ON, the lock-up control valve is moved somewhat to the right side,
causing the back pressure (F2) to lower. This allows a greater amount of the fluid (Fl) to work on the lock-up clutch
so as to engage the clutch. The back pressure (F2) which still exists prevents the clutch from engaging fully.
When used, "left" or "right" indicates direction on the flow chart.
NOTE:
14-42
Lock-up Control Solenoid Valve B: ON
T H R O T T L E B P R E S S U R E