Honda Acura NSX 1991 Service Manual page 403

Electronic Control System
The electronic control system consists of the A/T control unit, sensors, a linear solenoid and 4 solenoid valves. Shifting
and lock-up are electronically controlled for comfortable driving under all conditions.
The A/T control unit is located on the insulator center bulkhead, behind the driver's seat.
Shift control
Shifting is related to engine torque through the linear solenoid used to operate throttle valve B which is controlled by
the A/T control unit the control throttle pressure.
Getting a signal from each sensor, the A/T control unit detects the appropriate gear shifting and activates shift control
solenoid valves A and/or B.
The combination of driving signals to shift control solenoid valves A and B is shown in the table below.
Shift control sol. valve
Range (gear)
q
(2nd)
q q q
q q
(2nd)
Lock-up control
From sensor input signals, the A/T control unit detects whether to turn the lock-up ON or OFF and activates lock-up
control solenoid valve A and/or B accordingly.
The combination of driving signals to lock-up control solenoid valves A and B is shown in the table below.
Solenoid valve A
Lock-up condition
Lock-up OFF
Lock-up, slight
Lock-up, half
Lock-up, full
Lock-up
during deceleration
A B
OFF ON
ON OFF
ON OFF
OFF OFF
B
OFF OFF
ON OFF
ON
ON
ON
ON
Duty operation
ON
OFF *ON
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