Fiat Bravo Service Manual page 373

Engine
Fuel system
10.
Bravo
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20v
1. Rpm sensor
2. Toothed pulley
3. Engine flywheel
RPM A N D TDC SENSOR
(0.281.002.102)
The sensor designed to detect the rpm and
TDC is the inductive type, i.e. it operates by
varying the magnetic field created by the
teeth on a toothed pulley (flywheel) inside
the crankcase and fixed to the rear coun­
ter-weight for the crankshaft. In this way the
sensor is fixed to the crankcase and the
checks and adjustments of the gap and the
angular position are no longer necessary.
The teeth which pass in front of the sensor,
alter the gap between the pulley and the sen­
sor; the flow dispersed, which consequently
varies, produces an alternating voltage which
depends on the number of revs.
The flywheel has 58 teeth plus a space equiv­
alent to the two missing teeth.
The reference defined by the space for the
two missing teeth constitutes the basis for
detecting the synchronism point (TDC).
For a more detailed description of the operat­
ing principle, refer to the Fuel System section
for the 1581 16v engine.
Removing-refitting
Position the vehicle on a lift, then working
from underneath the vehicle:
- Disconnect the electrical connector;
- undo the bolt fixing the sensor and remove
it from its housing.
Wiring connector
The sensor is connected to the electronic
control unit (pins 48 and 49) by means of
twisted cables covered by a screened anti-in­
terference outer casing connected to earth.
NOTE The numbers indicate the corre­
sponding control unit pins
Checking the resistance
The resistance of the sensor can be measured
by disconnecting the connector and con­
necting an ohmmeter to the sensor.
Resistance: 774-946 ohm at 2 0 C
22 Print no. 506.670