General System Description

PURPOSE
The multi-point injection system maintains emission levels and fuel economy within government agency standards, while optimizing driveability. The system consists of an engine control module, control relay, wiring, sensors and actuators.

OPERATION
The engine control module uses an 8-bit microprocessor, random access memory, read only memory and an input/output interface. The control relay supplies positive current to the purge solenoid, engine control module and injectors. It also supplies current to the fuel pump during starting.

The system also performs self-diagnostic procedures and provides back-up functions if certain circuits fail.

SENSORS/INPUTS
- A/C control unit
- Volume air flow sensor
- Barometric pressure sensor
- Battery voltage
- Coolant temperature switch (A/C only)
- Crankshaft angle sensor
- EGR temperature sensor
- Engine coolant temperature sensor
- Heated oxygen sensor
- Idle position switch
- Ignition switch
- Ignition timing adjustment connector
- Transaxle range switch (A/T only)
- Intake air temperature sensor
- Power steering oil pressure switch
- Throttle position sensor
- Vehicle speed sensor
- Camshaft position sensor

ACTUATORS/OUTPUTS
- A/C relay
- Malfunction indicator lamp
- Exhaust gas recirculation solenoid
- Fuel injector
- Fuel pump
- Fuel pump check connector
- Idle speed control servo
- Power transistor
- Purge control solenoid





MALFUNCTION INDICATOR LIGHT
If a component or system malfunction is detected, the engine control module will illuminate the malfunction indicator light and record the corresponding diagnostic trouble code(s) in memory. However, when the engine control unit judges that the component or system has returned to normal, the engine control module will turn off the malfunction indicator light. If the ignition switch is turned OFF and then ON again, the engine control module 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 engine control module will store diagnostic trouble code 36 in memory and illuminate the malfunction indicator light.