Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
192
31.
DTC
P2228
Atmosphere pressure sensor output voltage is too low.
P2229 Atmosphere pressure sensor output voltage is too high.
Fault Description: Atmosphere pressure indicates connection of ignition switch. When engine stops operation,
control module calculates atmosphere pressure with signals sent by intake manifold absolute pressure sensor. Intake
manifold absolute pressure sensor responses to internal pressure changes of intake manifold and the pressure changes
according to different engine loads. Intake manifold absolute pressure sensor possesses circuits as follows:
5V reference voltage circuit
Low reference voltage circuit
Intake manifold absolute pressure sensor signal circuit
ECU provides intake manifold absolute pressure sensor with 5V voltage via 5V reference voltage circuit. ECU
supplies grounding via low reference voltage circuit and intake manifold absolute pressure sensor provides ECU with
a signal via signal circuit. This signal is related to intake manifold internal pressure changes. When ignition switch is
connected and engine is shut down, intake manifold absolute pressure sensor displays signals of atmosphere pressure.
In the case of engine running with wide open throttle, reading of atmosphere pressure will be renewed. ECU
determines whether voltage exceeds normal range via detecting intake manifold absolute pressure sensor signals.
When intake manifold absolute pressure sensor displays atmosphere pressure, if sensor signal voltage is not in
specified range, DTC occurs.
Diagnosis Hint: When ignition switch is connected and engine is shut down, intake manifold pressure equals to
atmosphere pressure and signal voltage is low level. ECU takes this information as vehicle elevation indication.
Moreover, to make comparison between this reading with that of an intact vehicle which possesses the same sensor is
a good method for sensor accuracy inspection. D-value of two readings should not exceed 0.4V. It is necessary to
carry out comprehensive inspection to pressure source of supercharger pressure sensor in order to check intake system
for clogging.
In the case of engine start, intake manifold absolute pressure sensor can detect any change of manifold pressure. This
test is carried out to determine sensor lag at a certain value.
In the case of normal intake manifold absolute pressure sensor, it will make rapid response to changes of acceleration
pedal positions and it should not be “lagged” or slower than changes of acceleration pedal position.
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