Ford Corsar Repair Manual page 255

E.C.C.S. DESCRIPTION
-
E.C.C.S. Components
[
KA24E -
1
SE F297
H
180" signal slit for No. 1 cylinder
Rotor plate
SEF863B
Battery
source
Air f!ow Output voltage
E.C.C.S.
meter
unit
Ground
109
Temperature
compensation resistor
.
l ,
R H : Hot wire reststance
R
K
: Temperature compensation resistance
R A , R
B : Constant resistance S E F 6 1 7 B
E.C.C.S. Control Unit (E.C.U.)
The E.C.U. consists of a microcomputer, inspection lamps, a
diagnostic mode selector, and connectors for signal input and
output and for power supply. The unit controls the engine.
Crank Angle Sensor
The crank angle sensor is a basic component of the entire
E.C.C.S. It monitors engine speed and piston position, and
sends signals to the E.C.U. to control fuel injection, ignition
timing and other functions.
The crank angle sensor has a rotor plate and a wave-forming
circuit. The rotor plate has 360 slits for 1" signal and 4 slits for
180" signal. Light Emitting Diodes (L.E.D.) and photo diodes are
built in the wave-forming circuit.
When the rotor plate passes between the L.E.D. and the photo
diode, the slits in the rotor plate continually cut the light being
transmitted to the photo diode from the L.E.D. This generates
roug h-shaped pulses which are converted into on-off signals by
the wave-forming circuit, which are then sent to the E.C.U.
Air Flow Meter
The air flow meter measures the mass flow rate of inrake air.
Measurements are made so that the control circuit will emit an
electrical output signal corresponding to the amount of heat
dissipated from a hot wire placed in the stream of intake air.
The airflow past the hot wire removes the heat from the hot
wire. The temperature of the hot wire is very sensitive to the
mass flow rate. The higher the temperature of the hot wire, the
greater its resistance value. This temperature change (resis-
tance) is determined by the mass air flow rate. The control
circuit accurately regulates current (I) in relation to the varying
resistance value (R,) so that V , always equals V , . The air flow
meter transmits a voltage value V , to the control unit where the
output is converted into an intake air signal.