Engine Control Module: Description and Operation

The electronic control unit (ECU) consists of an 8-bit microprocessor that uses all of the engine and vehicle operations sensors to determine the proper amount of fuel required to maintain the correct air-fuel ratio for minimum exhaust emissions. The ECU also controls (part or all of) the operation of the secondary air, electric choke, idle speed and distributor advance control systems. The ECU does not have on-board diagnostic functions, but can be tested with a Mitsubishi FBC checker or a suitable multi-meter.