Operation Section
1
–
47
(1) Pressure Limiter
• The pressure limiter opens to release the pressure if abnormally high pressure is generated. If pressure within the rail
becomes abnormally high, the pressure limiter operates (opens). It resumes operation (closes) after the pressure falls
to a certain level. Fuel released by the pressure limiter returns to the fuel tank.
< NOTE >
The operating pressures for the pressure limiter depend on the vehicle model and are approximately 140-230MPa for
the valve opening pressure, and approximately 30-50MPa for the valve closing pressure.
(2) Rail Pressure Sensor (Pc Sensor)
• The rail pressure sensor (Pc sensor) is installed on the rail. It detects the fuel pressure in the rail and sends a signal
to the engine ECU. This is a semi-conductor sensor that uses the piezo-electric effect of the electrical resistance vary-
ing when pressure is applied to a silicon element.
• There are also rail pressure sensors that have dual systems to provide a backup in case of breakdown. The output
voltage is offset.
Pressure Limiter
Leak
(To Fuel Tank)
Valve Open
Valve Close
Rail Pressure
Abnormally High Pressure
Return
Q000855E
GND
Vout
Sensor Wiring Diagram
Common Rail
Pressure Characteristic
Output
Voltage
-
Rail Pressure
Output Voltage
Vcc
+5V
ECU
Pc
Vout
Vcc=5V
GND
Vout
Vcc
Q000856E
Q000857E
E2S PR2 VCS
VC PR E2
Pc
Sensors
VC
VCS
PR2
PR
E2
E2S
+5V
ECU
ECU
Vout/Vcc
Vcc=5V
Rail Pressure
Output Voltage 1
Output Voltage 2
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