Ch 6 page 73
ELECTRICAL SYSTEM
SHOP MANUAL
Fuel pressure sensor
Control unit EMS S8
The engine control unit controls the engine functions.
The fuel pressure sensor informs the engine control unit of the
current fuel pressure in the accumulator.
Function:
The fuel pressure sensor registers and informs the engine control
unit of the current fuel pressure in the accumulator.
The engine control unit compares the measured fuel pressure
with the fuel pressure requested and calculates how much fuel
the fuel inlet metering valve should convey to the high pressure
pump so that the correct fuel pressure is obtained in the accumu-
lator.
The engine control unit registers the voltage from the sensor. The
signal voltage is directly proportional to the fuel pressure. A high
pressure gives a high voltage and vice versa.
If there are any faults with the signal, the engine control unit will
operate according to a preset pressure value while at the same
time generating a fault code. As a safety measure, engine torque
is limited.
Figure 60
Figure 59
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