Engine JAC HFC4DA1-2C. Service manual — part 37

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

147

Fault Tree:

Turn off the ignition switch and check the fuel

injector connector.

Connector fault

Repair accordingly.

Disconnect the fuel injector and turn on the ignition

switch.

Does the problem still exist?

Refer to “Inspection of Fuel Injector

Wiring” listed below.

Clear the DTC, turn off the ignition switch, reconnect

the fuel injector and turn on the ignition switch.

Does the problem reoccur?

Replace relevant fuel injector and

update the ECU data.

Repeat the above procedures for other fuel injectors.

Check the wiring of fuel injector.

Check the ECU connector.

Connector fault

Repair accordingly.

Check continuity and insulating property.

Electrical fault

Repair the harness.

Get the Technical Support.

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

148

10.

DTC

P0251

The control line of fuel level control unit is open.

P0252

The ECU internal driver module of fuel level control unit is overheating.

P0253

The control line of fuel level control unit is short to ground.

P0254

The control line of fuel level control unit is short to high level.

Fault Description: The fuel metering unit is for adjusting the fuel supply and the fuel pressure. When the control coil
of metering unit is off, the inlet fuel metering proportional valve of the unit shall be closed, cutting off the fuel
supplied to the high pressure fuel pump plunger component. When the control coil of metering unit is electrified, the
ECU shall change the fuel inlet sectional area of metering component via pulse signal according to the actual demand,
through which, the fuel supplied to the high pressure fuel pump plunger component shall be changed. If the fuel
metering control signal voltage detected by ECU is abnormal, the DTC shall be generated.

Diagnosis Hint: The metering component is mounted at the fuel inlet of high pressure pump. The engine’s fuel
supply shall be affected directly by the opening sectional area of the fuel metering unit control valve. Provided that the
fuel metering unit control line is normally connected, monitor the engine fuel supply amount and pressure while
moving relevant connector and wire to check if any fault is triggered. If any, the indication of fault diagnostic unit
shall change. This is help for locating the intermittent failure.

The intermittent failure may be caused by poor contact of control part. As for poor contact between ECU and fuel
metering unit, please check the ECU harness connector for the following conditions:

− Loose terminal

− Poor matching and connection

− Breakage of keeper

− Distortion or damage of terminal

− Poor contact between terminal and wire

Check the harness for any damage. If the harness appears normal, observe the fuel pressure indicated on the diagnostic
tool while moving relevant connector and harness of fuel metering unit. If the pressure indication changes, there must
be failure in that part.

Terminal ECU

A19

Power supply terminal of fuel metering unit

A49

Signal terminal of fuel metering unit

Control of fuel metering unit

Fuel metering unit

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

149

Fault Tree:

Check the connector of fuel metering unit.

Repair accordingly.

Repair accordingly.

Repair the harness.

Repair the fuel metering unit.

Get the Technical Support.

Connector fault

Check the ECU connector.

Connector fault

Check continuity and insulating property.

Electrical fault

Resistance fault

Measure the resistance of fuel metering unit

(it is about 5.3 Ohms at 20℃)

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

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11.

DTC

P0335

No signal from crankshaft sensor

P0336

False signal from crankshaft sensor

Diagnosis Hint: The signal of crankshaft position (CKP) sensor is used for indicating the rotary speed and position of
crankshaft. The CKP sensor shall generate an AC voltage of different amplitude and frequency. The frequency relies
on the rotary speed of crankshaft and the output AC voltage relies on the crankshaft position. The CKP sensor shall
coordinate with a 58X variable reluctance rotor fixed on the crankshaft. The ECU can synchronize the timing control
for fuel injectors according to the input signals of CKP sensor and camshaft position sensor. The CKP sensor can also
be applied for testing misfire and tachometer indication. The signal circuit and the low reference voltage circuit of
CKP sensor are directly connected to ECU. The shielded and grounded circuit should be grounded. In addition, when
the 1

st

and the 4

th

cylinders are at TDC, the CKP sensor shall also send a signal to ECU. The ECU shall monitor the

signals of CKP sensor and camshaft position sensor to determine whether the 1

st

cylinder is in compression stroke or

not. The circuits between CKP sensor and ECU include:

Signal circuit of CKP sensor

Low reference voltage circuit of CKP sensor

Shielded and grounded circuit

If the number of crankshaft position pulses sent out by the CKP sensor detected by the ECU is incorrect, the DTC
shall be generated.

Diagnosis Hint: There is failure in camshaft position sensor circuit.

CKP sensor variable reluctance rotor is dislocated or incorrectly installed.

Large crankshaft end play leads to dislocation of variable reluctance rotor.

There is blockage between CKP sensor and variable reluctance rotor.

Check connectors of CKP sensor and ECU for any corrosion.

Prior to maintenance, all fragments should be removed from the connector surfaces. Prior to diagnosis or replacement,
please check the connector gaskets to ensure they are properly installed to avoid ingress of any pollutant.

z Poor terminal connection – Check the harness connector for any loose terminal, mismatching, damaged keeper,

improper form or damage, poor contact between terminal and wire. Check if the matched terminal is adopted.
Check if the test tension is appropriate.

z Harness damage – Check the harness for any damage. If the harness appears normal, observe the indication on

the diagnostic tool while moving relevant connector and harness of the sensor. If the indication changes, there
must be failure in that part.

Wheel speed sensor

Signal

Ground

Shielded wire