Description & Operation: Notes

The Electronic Control Unit (ECU) receives signals from various sensors. ECU computes the signals and sends output signals to various control devices. The ECU is the main controlling device of the electronic control system. On Sedan, ECU is mounted below passenger seat. On Coupe, ECU is mounted under carpet, below passenger side of dash.

The ECU contains memories for the basic injector durations at various engine RPM and Manifold Absolute Pressures (MAP). The basic injector duration is read out of the memory of the ECU. The ECU modifies the basic injector duration according to input signals from various sensors to obtain the final injector duration.

The ECU controls cold start system, electric fuel pump and fuel cut-off systems. The ECU contains a fail-safe system to monitor sensors and detect any abnormality. This provides safe driving even if one or more of the sensors are faulty or the ECU malfunctions.

There are several sensors used to provide operating information to the ECU. They include Top Dead Center (TDC) sensor, Crank/Cylinder (CRK/CYL) sensors, Manifold Absolute Pressure (MAP) sensor, Atmospheric Pressure (PA) sensor, coolant temperature sensor, intake air temperature sensor, throttle angle sensor, front and rear oxygen sensors, Idle Mixture Adjuster (IMA) sensor and starter switch.

NOTE: TDC sensor and CRK/CYL sensor vary depending on vehicle application.

The electronic control system has a self-diagnostic function to help diagnose problems. This system uses a dash mounted PGM-FI warning light and one or 2 ECU mounted self-diagnostic lights. Vehicles use a Red LED light on ECU for system failure code and a Yellow LED light for idle speed adjustment. The PGM-FI warning light will glow for 2 seconds when ignition switch is turned to the "ON" position.