Acura 3.5 RL Manual page 505

Partial Lock-up
Torque Converter Clutch (Lock-up Control) Solenoid Valve A: ON Torque Converter Clutch (Lock-up Control) Solenoid
Valve B: OFF
The PCM switches the solenoid valve A on to release the modulator pressure in the left cavity of the lock-up shift valve.
The modulator pressure in the right cavity of the lock-up shift valve overcomes the spring force; thus the lock-up shift
valve is moved to the left side.
The line pressure is then separated into the two passages to the torque converter:
Torque Converter Inner Pressure: enters into right side to engage lock-up clutch
Torque Converter Back Pressure: enters into left side to disengage lock-up clutch
The back pressure (F2) is regulated by the lock-up control valve, whereas the position of the lock-up timing valve is deter-
mined by the throttle B pressure, tension of the valve spring, and pressure regulated by the modulator valve. Also the posi-
tion of the lock-up control valve is determined by the back pressure of the lock-up control valve and torque converter pres-
sure regulated by the check valve. With the torque converter clutch solenoid valve B kept off, the modulator pressure is main-
tained in the left side of the lock-up control valve; in other words, the lock-up control valve is moved slightly to the right side.
This slight movement of the lock-up control valve causes the back pressure to be lowered slightly, resulting in partial lock-up.
NOTE: When used, "left" or "right" indicates direction on the hydraulic circuit.