Engine Control Module: Description and Operation

ENGINE CONTROL MODULE (ECM)/POWERTRAIN CONTROL MODULE (PCM)
ECM (PCM) (1) is installed to the underside of the instrument panel at the passengers seat side. ECM is a precision unit consisting of microcomputer, A/D (Analog/Digital) converter, I/O (Input/Output) unit, etc.

It is an essential part of the electronic control system, for its functions include not only such a major function as to control fuel injector, idle air control valve, fuel pump relay, etc. but also on- board diagnostic system (self-diagnosis function) and fail-safe function as described.