Honda Acura NSX 1991 Service Manual page 413

Modulator Valve
The modulator valve maintains line pressure from the regulator which is supplied to shift control solenoid valves A/B
and lock-up control solenoid valves A/B, thus maintaining accurate shift and lock-up characteristics.
MODULATOR VALVE
2nd Orifice Control Valve
For smooth shifting between the 2nd and 3rd gear, the open pressure on the 2nd gear side is relieved through a fixed
orifice. The valve also moves to equalize pressure differences between the 2nd and 3rd gear.
2nd Exhaust Valve
The 2nd exhaust valve is installed to release 2nd clutch pressure quickly when shifting from the range at which hydraulic
pressure is applied to the 2nd clutch to the N position.
2ND ORIFICE CONTROL VALVE
2ND EXHAUST VALVE