Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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3.
DTC P0087 The fuel pressure is below the lower limit.
P0088 The fuel pressure is above the upper limit.
P0191 The forward drift of common rail pressure sensor is too large.
P0192
The common rail pressure sensor output voltage is below the lower limit (the wiring
is short to ground).
P0193
The common rail pressure sensor output voltage is above the upper limit (the
wiring is open or short to high level).
P0194 The reverse drift of common rail pressure sensor is too large.
P1011 The positive deviation of rail pressure control is above the upper limit.
P1012 The positive deviation of rail pressure control exceeds the upper limit greatly.
P1013 The negative deviation of rail pressure control is below the lower limit.
Fault Description: The common rail pressure sensor shall make response to the change of fuel pressure in common
rail pipe. The pressure changes with the engine load. The ECU shall supply 5V voltage to the 5V reference voltage
circuit of common rail pressure sensor and also supply grounding for the low reference voltage circuit. The common
rail pressure sensor shall provide a signal that is related to the change of fuel pressure in common rail pipe to ECU via
the common rail pressure sensor signal circuit. When the fuel pressure in common rail pipe is relatively low (for
example: during idling period), the low level signal voltage shall be detected by the ECU. When it is relatively high
(for example: with the accelerator pedal fully open (WOT)), the high level signal voltage shall be detected. The
common rail pressure sensor provides an important parameter for determining engine operation. When its signal is
lost, the engine shall stop operation. The common rail pressure sensor includes the following circuits:
z A 5V reference voltage circuit
z A low reference voltage circuit
z A common rail pressure sensor signal circuit
If the common rail pressure sensor signal detected by ECU is beyond the set range, relevant DTC shall be generated.
Diagnosis Hint: When the ignition switch is turned on with engine off, the pressure in common rail pipe is zero and
the signal voltage level is low. By comparing the readings with those of the same sensor that is known good, the
accuracy of the suspicious sensor can be checked. Their difference should be no more than 0.4V. Perform overall
inspection for common rail pressure sensor to see if it is damaged.
During engine starting, any pressure change in the common rail pipe should be detected by the common rail pressure
sensor, through which, we can determine if the sensor is stuck at a certain value.
The normal common rail pressure sensor shall make quick response to the change of accelerator pedal position, so its
slow action should not appear or it should not act slower than the change of accelerator pedal position.
Common rail
pressure sensor
5V power supply
Rail pressure signal
Ground
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