XC90 AWD V8-4.4L VIN 85 B8444S (2005)
Engine Control Module: Description and Operation
The engine control module (ECM) controls, amongst others, the following functions:
Evaporative emission system (EVAP) valve
engine cooling fan (FC)
Air conditioning (A/C) compressor
The engine control module (ECM) is supplied with battery power (Ubat) via fuses in the central electronic module (CEM) and in the relay/fuse box,
To prevent certain stored data 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, 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 in the engine control module (ECM).
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 interprets the signals from the different sensors and how the components and functions should be controlled.
The engine control module (ECM) has several self-learning (adaptive) functions. It continually adapts ongoing calculations to changing circumstances
(such as wear, air leaks, differences in fuel).
Emissions are kept low through efficient management of the injection period, ignition, evaporative emission system (EVAP) valve, camshafts etc. Faults
which affect emissions for example can be detected by running diagnostics for functions and components.
The engine control module (ECM) is located on the air cleaner (ACL) box in the engine compartment. A temperature sensor and atmospheric pressure
sensor are integrated in the engine control module (ECM).
The engine control module (ECM) communicates with other control modules using controller area network (CAN) communication or LIN
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 temperature sensor
mass air flow (MAF) sensor
throttle position (TP) sensor
Mathematical calculations and signals from certain components are used to calculate the substitute values. Other substitute values are fixed, predefined