Fiat Bravo Service Manual page 125

Bravo-Brava
1. Rpm sensor
2. Toothed pulley
3. Engine flywheel
Copyright Fiat Auto
12v
R P M AND
(0.281.002.102)
The sensor responsible for measuring rpm
and T D C is inductive, in other words it works
by means of changes in a magnetic field gen-
erated by teeth passing in front of a toothed
pulley (phonic wheel) situated inside the en-
gine block. The sensor is thus fastened to the
engine block and it is no longer necessary to
check and adjust gap or angular position.
The passage of teeth in front of the sensor al-
ter the gap between pulley and sensor. The
dispersed flow alters as a result to set up an
alternating voltage with amplitude depen-
dent on rpm.
The phonic wheel consists of 58 teeth plus a
space equivalent to the gap left by two miss-
ing teeth.
The reference point defined by the gap left by
two missing teeth is used as a basis for
recording synchronism point ( T D C ) .
Refer to Fuel System section for the 1581
16v engine for a more detailed description of
sensor operation.
Removing - ref itti ng
Position vehicle on a lift, then work from be-
low the vehicle and proceed as follows:
- Disconnect electrical connection;
- unscrew screw retaining sensor and with-
draw from housing.
Wiring connector
The sensor is connected to the E C U (pin 16 e
32) by means of twisted wires covered by an
earthed interference-proof shielded sheath.
NOTE The numbers in boxes indicate the
corresponding gpntroi unit pins.
Checking resistance
Sensor resistance may be measured by dis-
connecting the connector and connecting an
ohmmeter to the sensor terminals.
Resistance: 774-946 ohm at 20 C
Engine
Fuel system
10.
T D C S E N S O R
2 3