Ford Corsar Repair Manual page 173

E.C.C.S. DESCRIPTION
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E.C.C.S. Components
ELECTRONIC CONTROL MODULE (E.C.M.)
The E.C.M. consists of a microcomputer, connections for signal
input, output and power supply. The E.C.M. controls the amount of
fuel injected, ignition timing, engine idle speed, spark plug
switching, radiator cooling fans, air conditioner compressor (where
fitted), fuel pump, autotrans torque converter function, air flow-
meter burn off function and E.C.M. lamp operation. Additionally the
control unit incorporates a diagnostic system and a failsafe system
to provide substitution for certain components should they fail along
with a limp processor t o provide limited operation of the system
should the main processor fail.
Distributor
(HALL EFFECT) SENSOR
The hall effect sensor is a basic signal sensor for the entire E.C.C.S.
System. It monitors engine speed and sends a signal t o the E.C.M.
The hall effect sensor has a rotor and stator assembly. The rotor
consists of four windows and four metal tabs that rotate past the
stator assembly (hall effect switch). The stator assembly consists
of a hall effect device and a magnet. As the rotor rotates,
alternatively a metal tab, then a window pass between the hall effect
device and the magnet. The resulting changes t o magnetic flux cre-
ate an ON/OFF pulse within the device, which is then sent to the
E.C.M.
WATER TEMPERATURE SENSOR
The water temperature sensor monitors changes in cooling water
temperature and transmits a signal t o the E.C.C.S. control unit. The
temperature sensing unit employs a thermistor which is sensitive to
the change in temperature. Electrical resistance of the thermistor
decreases in response t o the temperature rise.
THROTTLE POSITION SENSOR (TPS)
The throttle position sensor is attached to the throttle chamber and
actuates in response to accelerator pedal movement. The TPS is a
potentiometer which provides an output voltage that varies accord-
ing to throttle valve opening. In this way the ECM can detect both
the amount of throttle opening and the rate of throttle opening or
closing.
The E.C.M. uses the idle reading as a zero reading (0% throttle), so
no T.P.S. adjustment is necessary.