Engine JAC HFC4DA1-2C. Manual — part 42

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

167

Fault Tree:

Check the relay connector.

Connector fault

Repair accordingly.

Check the ECU connector.

Connector fault

Repair accordingly.

Repair the harness.

Check continuity and insulating property.

Electrical fault

Replace the relay (running ISO
circulation.)

Fault of ISO circulation

Get the Technical Support.

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

168

20.

DTC

P0704

Clutch signals are unreliable.

Fault Description: Transmission control unit (TCU) is integrated with engine control unit (ECU) and calculates
optimal time and speed for clutch engagement according to feedback information from sensors of accelerator pedal,
transmission gear position, transmission input/output shaft speed, engine speed, throttle opening and etc. Automatic
transmission (AT) actuating mechanism consists of electric oil pump, solenoid valve and clutch cylinder. When ECU
gives command to drive electric oil pump, high-pressure fluid generated in the pump goes through solenoid valve and
gets into clutch cylinder. ECU controls magnitude of current of solenoid valve for the control of fluid flow and fluid
passage change. Thus piston movement of clutch cylinder is realized in order to complete clutch operation during
vehicle starting and shift. In the case of inconformity between clutch signal and actual condition, DTC occurs.

Diagnosis Hint: clutch switch fault

Check switch wire harness (Check Terminal 58 of ECU for open circuit, short circuit and poor contact.)

Check switch power supply voltage and operation condition.

Determine ECU replacement according to actual condition.

Terminals ECU

K55 Clutch

switch

signal

Clutch switch

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

169

Fault Tree:

Get the Technical Support.

Repair accordingly.

Repair the harness.

Replace the clutch switch.

Check clutch switch.

Clutch switch fault

Check clutch switch harness.

Harness fault

Check clutch switch power supply voltage.

Power supply signals are distorted.

Replace ECU and check

Does the problem still exist?

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

170

21.

DTC P0650

There are faults (short circuit or open circuit) in ECU OBD malfunction
indicator lamp (MIL) output connecting wire.

P1619

Connection of ECU system MIL output connecting wire is short to high
level.

P161A

Connection of ECU system MIL output connecting wire is short to ground.

P161B

ECU system MIL output connecting wire is open.

P161C

ECU system MIL drive module is overheated.

Fault Description: Malfunction indicator lamps (MIL) are located on instrument panel cluster (IPC). MILs inform
driver about fault generation and necessary maintenance for engine control system. Control module monitors MIL
control circuit for inconformity of commands for MILs. For example, when MIL is disconnected by command, control
module monitors low voltage or when MIL is connected by command, control module monitors high voltage. This is
indicated that there are faults. When control module discovers incorrect voltage or overhigh temperature of MIL
control circuit, DTC occurs. In the case of 20 samplings for output status of MIL drive, open circuit or overhigh
temperature faults are detected in 15 samplings at least. There are 100msec for each sampling. ECU detects incorrect
output status or overlarge current of MIL drive and such status lasts for more than 2sec; for every 10 samplings of
MIL drive output status, there are short circuit faults in 5 samplings at least with time consumption for each sampling
process as 12.5msec and ECU detects short circuit for more than 1sec under MIL drive output status. In the case of
conditions above, DTCs occur.

Diagnosis Hint: When short circuit fault is detected, control module should stop starting MIL drive within remained
travel. Control module records operation condition when diagnosis is failed. For the first diagnosis failure, control
module will keep this information in fault record. If diagnosis failure occurs during the second continuous ignition
cycle, control module records operation condition under diagnosis failure and writes the operation condition in frozen
fault condition and updates fault record.

Terminal ECU

K70

System MIL output signal

K71 OBD

indicator

lamp

Malfunction indicator lamp (MIL)

OBD indicator lamp