General System Description

The Computerized Engine Control System is built around the electronic Multi-Point Injection (MPI) Control Unit. The Engine Controller constantly monitors signals from various sensors and responds by actuating output devices to maintain optimum performance and fuel economy.

INPUTS

A/C ON-OFF Switch
Barometric Pressure Sensor
Camshaft Position (TDC) Sensor
Crankshaft Position Sensor
Engine Coolant Temperature Sensor
Exhaust Gas Temperature Sensor
Heated Oxygen Sensor Front
Heated Oxygen Sensor Rear
Idle Air Control Valve Position Sensor
Idle Position Switch
Intake Air Temperature Sensor
Ignition Switch ST terminal (start signal)
Power Steering Oil Pressure Switch
Park/Neutral Position Switch (A/T ONLY)
Power Supply (Ignition Switch Coupled)
Power Supply (Battery Backup)
Throttle Position Sensor
Vehicle Speed Sensor
Volume Air Flow Sensor

OUTPUTS

Air-Conditioner Power Relay
Evaporative Emission Purge Control Solenoid Valve
EGR Control Solenoid Valve
Fuel Injector Pulse Width
Idle Air Control (IAC) Motor
Ignition Timing Power Transistor
Multiport Fuel Injection Relay
Malfunction Indicator light
Fan Motor Relay And A/C Refrigerant Medium Pressure Switch.
Self-Diagnosis Output

Check Engine / Malfunction Indicator Lamp:

MALFUNCTION INDICATOR LIGHT

If a component or system malfunction is detected, the Engine Controller will illuminate the "MALFUNCTION INDICATOR LIGHT" and record the corresponding trouble code(s) in memory. However, when the engine control unit judges that the component or system has returned to normal, the MPI control unit will turn off the Malfunction Indicator Light. If the ignition switch is turned OFF and then ON again, the Engine Controller will not illuminate the Malfunction Indicator Light until the irregularity is detected again.
Under normal conditions, the Malfunction Indicator Light will be lit for 2.5 seconds immediately after the engine is started. This is to indicate that the light is not burned out and is operating normally.

NOTE: When the Ignition Timing Adjustment Terminal is shorted to ground during ignition timing inspection/adjustment procedures, the Control Unit will store a Fault Code 36 in memory and illuminate the Malfunction Indicator Light.