Fiat 1998 Marea Weekend, Service Manual

Page: 241 / 846

Marea- Marea Weekend 0
99 range
Engine
Fuel system
_ n n _
1 2
i_r
— L
3
2 B -
-=-
11B
10.
VEHICLE SPEED SENSOR
This sensor is positioned at the differential
output, by the left driveshaft coupling and
transmits information concerning the vehicle
speed to the speedometer: the signal is then
sent to the engine control unit.
The sensor is the Hall effect type and is cali-
brated so that a given distance corresponds to
each impulse: it is therefore possible to calcu-
late the vehicle speed according to the fre-
quency of the impulses.
POWER ASSISTED STEERING SENSOR
This sensor, fitted on the pump high pressure
outlet pipe, consists of a pressure switch
which closes when the hydraulic pressure ex-
ceeds a level corresponding to the steering
close to the end of travel position: the infor-
mation is used to manage the idle speed con-
trol actuator in advance of the absorption of
power due to steering.
DETONATION SENSOR
This is a piezoelectric type sensor fitted on the
cylinder block/crankcase, symmetrical in rela-
tion to the pairs of cylinders 1 -2 and 3-4.
This position is determined by the need to de-
tect the onset of detonation in the same way in
all cylinders.
When the engine is knocking, cylinder
block/crankcase vibrations of a particular fre-
quency are produced and they are transformed
by the sensor into a voltage signal proportional
to their intensity.
Connector wiring
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