Idle Speed Control — INPUT/OUTPUT SIGNAL LINE
EF & EC-18prose procedureNeutral switch applies to M/T models; Inhibitor switch applies to A/T models.
ENGINE AND EMISSION CONTROL SYSTEM DESCRIPTION
Idle Speed Control
INPUT/OUTPUT SIGNAL LINE
Idle Speed Control Input/Output Signal Line
Components (10)
Crank angle sensorEngine temperature sensorIgnition switchIdle switchNeutral switch (M/T) / Inhibitor switch (A/T)Air conditioner switchBatteryVehicle speed sensorE.C.C.S. control unitAuxiliary air control valve
Connections (9)
Crank angle sensor
Crank angle sensorE.C.C.S. control unit— Engine speed
Engine temperature sensor
Engine temperature sensorE.C.C.S. control unit— Engine coolant temperature
Ignition switch
Ignition switchE.C.C.S. control unit— Start signal
Idle switch
Idle switchE.C.C.S. control unit— Throttle valve idle position
Neutral switch (M/T) / Inhibitor switch (A/T)
Neutral switch (M/T) / Inhibitor switch (A/T)E.C.C.S. control unit— Neutral position
Air conditioner switch
Air conditioner switchE.C.C.S. control unit— Air conditioner operation
Battery
BatteryE.C.C.S. control unit— Battery voltage
Vehicle speed sensor
Vehicle speed sensorE.C.C.S. control unit— Vehicle speed
E.C.C.S. control unit
E.C.C.S. control unitAuxiliary air control valve
SYSTEM DESCRIPTION
This system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine adjustment of the amount of air which by-passes the throttle valve via A.A.C. valve. The A.A.C. valve repeats ON/OFF operation according to the signal sent from the E.C.U. The crank angle sensor detects the actual engine speed and sends a signal to the E.C.U. The E.C.U. then controls the ON/OFF time of the A.A.C. valve so that engine speed coincides with the target value memorized in ROM. The target engine speed is the lowest speed at which the engine can operate steadily. The optimum value stored in the ROM is determined by taking into consideration various engine conditions, such as noise and vibration transmitted to the compartment, fuel consumption, and engine load.