Fiat 1998 Marea Weekend, Service Manual

Page: 348 / 846

Marea-Marea Weekend®^
99 range
Engine
Fuel system
4A23LJ01
1. Rpm sensor
2. Toothed pulley
3. Engine flywheel
;
•
L.
r
10.
ENGINE RPM AND TDC SENSOR
(0.261.210.160)
This sensor which measures the engine speed
and TDC is the inductive type, i.e. it operates
through the variation in the magnetic field
produced by the passing of the teeth on a
toothed pulley (flywheel) located inside the
cylinder block/crankcase and fixed to the
crankshaft rear counter-weight. In this way the
sensor is fixed to the cylinder block/crankcase
and the gap and the angular position no longer
need to be checked or adjusted.
The teeth which pass in front of the sensor al-
ter the gap between the pulley and the sensor;
the dispersed flow, which varies as a result,
produces an alternating voltage whose fre-
quency depends on the number of revs.
The flywheel has 58 teeth plus a space
equivalent to the missing two teeth.
The reference defined by the space for the
missing two teeth constitutes the basis for de-
tecting the point of synchronism (TDC).
Removing-refitting
Position the vehicle on a lift then, working
from the underneath of the vehicle:
- disconnect the electrical connection;
- undo the bolt fixing the senor and remove it
from its housing.
Connector wiring
The sensor is connected to the electronic con-
trol unit (pins M10 and M59) by means of
twisted cables covered by an outer casing.
The numbers indicate the corresponding con-
trol unit pins.
Checking the resistance
The sensor resistance can be measured by dis-
connecting the connector and connecting an
ohmmeter to the sensor terminals.
Resistance: 774-946 ohm at 20°C
Copyright by Fiat Auto
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