Engine JAC HFC4DA1-2C. Manual — part 43

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

171

Fault Tree:

检查仪表板与ECU的连接

做必要的修理

接插件问题

检查连续性和绝缘性

Y

N

电气问题

Y

修理线束

更换相应的器件

N

问题仍存在

Y

联系技术支持

Get the Technical Support.

Repair the harness.

Repair accordingly.

Check connection between instrument panel and ECU.

Connector fault

Electrical fault

Check continuity and insulating property..

Replace corresponding components.

Does the problem still exist?

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

172

22.

DTC P0100

Mass air flow (MAF) signals measured by air flow meter without correction
are too strong or too weak (Connection is in open circuit or short circuit).

P0101

Mass air flow (MAF) signals measured by air flow meter with correction are
too strong or too weak (Connection is in open circuit or short circuit).

P0102

Mass air flow sensor negative drift

P0103

Mass air flow sensor positive drift

P0104

Mass air flow sensor zero drift

P1100

Air mass flowmeter software correction is excessive.

Fault Description: Mass air flow (MAF) sensor is an air flow meter which is used in measurement of air inflow of
engine. ECU correctly supplies fuel supply with the use of signals from mass air flow sensor for all engine speeds and
loads. In the case of small air inflow of engine, it is indicated there is vehicle deceleration or engine idling. In the case
of large air inflow of engine, it is indicated there is vehicle acceleration or high engine load. Mass air flow (MAF)
sensor possesses circuits as follows:

One ignition 1 voltage circuit

One ground circuit

One signal circuit

ECU applies a voltage to sensor via signal circuit. The sensor uses the voltage to generate a corresponding frequency
for air inflow which gets through the sensor. During idle running, the frequency changes in the range around 2000Hz.
ECU calculates predicted air flow value with input signals from sensors as follows:

Atmosphere pressure in the case of ignition key connection

Intake manifold absolute pressure sensor

Intake air temperature sensor

Engine coolant temperature sensor

Engine speed

ECU compares mass air flow sensor frequency signal with predicted air flow valve and verify signal lag (lack of
change), too low or too high signal level under given operation condition with the comparison. When D-value
between actual mass air flow sensor frequency signal which is detected by ECU and air flow meter calculated value is
not in preconcerted range, DTC occurs.

Diagnosis Hint: Check mass air flow sensor harness and verify whether harness arrangement is too close to
components as follows:

Intake air temperature signal

Power supply

Intake air flow signal

Ground signal

Air flow meter

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

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— Additional accessories after sale

— Secondary ignition wires or coils

— Solenoid valve

— Relay

— Motor

In the case of idle running or deceleration, air flow goes through sensor may reach its minimum and this may lead to
DTC occurrence. Check down stream of mass air flow sensor for vacuum leaks. Check mass air flow sensing elements
for affixed dirt or scraps. Check intake system for water penetration. Once there is water in mass air flow sensor, it
will lead to sensor deviation and DTC occurrence.

Wide open throttle during vehicle acceleration for starting may lead to rapid parameter increase of mass air flow
sensor on fault diagnostic apparatus. In other words, 3-10g/sec during idle running will increase to 150g/sec for shift
from the 1

st

gear to the 2

nd

. If parameters do not increase, check intake system and exhaust system for clogging.

Check engine coolant temperature sensor for deviation or lag.

In the case of too high resistance in ignition 1 voltage circuit (i.e. equals to or more than 15Ω), DTC occurs.

Terminal ECU

K12

Intake air temperature signal

K20

Intake air flow signal

K63 Ground

signal

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

174

Fault Tree:

检查空气流量计接插件

做必要的修理

接插件问题

做必要的修理

检查ECU接插件

接插件问题

检查连续性和绝缘性

Y

N

Y

N

电气问题

Y

修理线束

更换空气流量计

N

问题仍否存在

Y

联系技术支持

Get the Technical Support.

Repair the harness.

Repair accordingly.

Repair accordingly.

Check air flow meter connectors.

Connector fault

Check ECU connectors.

Does the problem still exist?

Connector fault

Electrical fault

Check for continuity and insulating property.

Replace air flow meter.