Engine Control Module: Description and Operation
The engine control module (ECM) controls the following functions:
evaporative emission system (EVAP) valve
engine cooling fan (FC)
Air conditioning (A/C) compressor
alternator control module (ACM) (2005-).
The engine control module (ECM) is supplied with battery voltage (Ubat) via fuses in the central electronic module (CEM) and in the integrated
relay/fusebox in the engine compartment.
To prevent certain stored date from being erased from the engine control module (ECM) when the ignition is switched off, the control module also has a
30-supply. This supply is from the integrated relay/fusebox in the engine compartment.
The control module is grounded via the wiring which is connected at the right-hand suspension turret.
The engine control module (ECM) contains a voltage regulator which maintains a low voltage (5 V) in internal components in the control module such
The functions which require battery power (Ubat) and high output are controlled by external or internal power stages. For example ignition coils have
external power stages (integrated into the ignition coils) while the power stages for the injectors are integrated into the control module.
The micro-processor in the engine control module (ECM) receives signals from the different sensors and control modules in the vehicle. The
micro-processor uses a program which calculates how the signals from the different sensors and other control modules are to be interpreted and how the
components / functions need to be controlled.
The control module has several self-learning (adaptive) functions. It continually adapts ongoing calculations to changing circumstances (wear, air leaks,
differences between different fuels).
Emissions are kept low through efficient management of the injection period, ignition, evaporative emission system (EVAP) valve and camshafts etc.
Faults which affect emissions can be detected by running diagnostics for functions and components.
The engine control module (ECM) is in the intake system. It is cooled by the engine intake air.
The engine control module (ECM) communicates with other control modules using controller area network (CAN) communication.
The engine control module (ECM) checks activations, input and output signals and functions using an integrated diagnostic system. A diagnostic trouble
code (DTC) is stored if, after validation, the control module detects a fault. In certain cases the faulty signal is also replaced with a substitute value or
certain functions are limited.
For example, substitute values can be set for:
engine coolant temperature (ECT) sensor
mass air flow (MAF) sensor
throttle position (TP) sensor