Justy Hatchback 2WD L3-1.2L SOHC (MPFI) (1992)
Engine Control Module: Description and Operation
Computerized Engine Controls
PURPOSE
The ECU is a computer that calculates signals from various sensors and switches to judge engine operating conditions and sends output signals to
provide precise control and functioning of various systems. Main ECU control functions are:
^ Fuel injection control
^ Ignition system control
^ Idle speed control
^ Canister purge control
^ Fuel pump control
^ Air conditioner cut control
^ Self-diagnosis function
^ Fail-safe function
LOCATION
The ECU is located behind the left side of the dash board.
OPERATION
When the ECU is sending fixed signals without regard to oxygen sensor output voltage, the system is said to be in "open loop." Conversely, when
the control unit is computing signals based on oxygen sensor voltage, the system is said to be in "closed loop."
The ECU has built-in preprogrammed values that it will default to if system malfunctions are detected. This usually permits the vehicle to be