D21 Hardbody 2WD L4-2389cc 2.4L SOHC MFI (KA24E) (1990)
Idle Air Adjusting (I.A.A.) Unit
The I.A.A. unit is made up of the A.A.C. valve and air cut valve. It receives the signal from the E.C.U. and controls the idle speed at the preset value
under various conditions. The air cut valve prevents an abnormal rise of idle rpm when A.A.C. valve operates abnormally.
Auxiliary Air Control (A.A.C.) Valve
The A.A.C. valve is attached to the throttle chamber. The E.C.U. actuates the A.A.C. valve by an ON/OFF pulse. The longer that ON pulse is received,
the larger the amount of air that will flow through the A.A.C. valve. The A.A.C. valve adjusts idle speed to the specified value.
Power Steering Oil Pressure Switch
The power steering oil pressure switch is attached to the power steering high-pressure tube and detects the power steering load, sending the load signal to
the E.C.U. The E.C.U. then sends the idle-up signal to the A.A.C. valve.
Vehicle Speed Sensor
The vehicle speed sensor provides a vehicle speed signal to the E.C.U. The speed sensor consists of a reed switch, which is installed on the transmission
unit and transforms vehicle speed into a pulse signal.