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Yanmar 4BY - Water-in-Fuel Sensor; Crankshaft Speed Sensor

Yanmar 4BY
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ELECTRICAL AND ECU
12-18
BY Service Manual
Component Tests
Water-in-Fuel Sensor
This sensor monitors fuel for the presence of water
and sends the signal to the helm display. If water is
present, the resistance between the probes drops
below the threshold of 47 k-ohms and results in a
warning at the helm. It is mounted on the bottom of
the fuel filter / water separator.
The sensor output is not used by the ECU.
Results of Failed Sensor
Failure of the sensor results in:
Loss of water-in-fuel monitoring
If this sensor is defective, no P-codes will be
generated.
Test Values
No test values are available for this device
Figure 12-13
1 Pin A - Black wire
2 Pin B - Red wire
3 Pin C - Yellow wire
Crankshaft Speed Sensor
This sensor measures the speed of the crankshaft.
This value is compared with the camshaft speed by
the ECU. It is mounted on the rear crankshaft seal
housing at the rear of the engine. The ECU
supplies 5V and ground.
The sensor signal is used by the ECU for:
The calculation of the actual rotations of the
engine
The check of the starting conditions
The calculation of the injection rate at the starting
procedure
The control of the injection start
The calculation of the limitation of the injection
rate
The calculation if an external regulation of the
injection rate is necessary
The control of the glow plugs
The control of the injection rate
The control of the rail pressure
The control at idle speed
Results of Failed Sensor
Failure of the sensor results in:
Inability to start the engine. Engine can not run
without this sensor.
If this sensor is defective, the following P-codes
may be generated:
P0344 - disagreement between camshaft speed
sensor and crankshaft speed sensor
P2617 - no connection / short circuit
0004170
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