XC90 FWD L6-3.2L VIN 98 B6324S (2007)
Engine Control Module: Description and Operation
The Engine Control Module (ECM) uses the signal from the ignition switch to detect when the ignition key has been turned to position II or III. When
the key is in the ignition position (position II) or starting position (position III) a high signal (Ubat) is transmitted from the ignition switch to the engine
control module (ECM). The engine management system prepares for start-up (for example, temporarily activates the fuel pump (FP) relay). When the
flywheel in the engine rotates, the engine speed (RPM) sensor signal is used to keep the fuel pump (FP) relay activated.
The fuse in the fusebox in the passenger compartment supplies current to the ignition switch.
The central electronic module (CEM) has diagnostics for the ignition switch.
Transmission control module (TCM)
The engine control module (ECM) uses a directly connected signal from the transmission control module (TCM) in the start function (activating the
See Design and Function, Immobilizer/start inhibition.
Alternator control module (ACM)
See Design and Function, Alternator.
Engine speed (RPM) sensor
The engine speed (RPM) sensor provides the engine control module (ECM) with information about the speed and position of the crankshaft. The engine
control module (ECM) is able to use the signal from the engine speed (RPM) sensor to determine when a piston is approaching top dead center (TDC).