JAC S2. Engine. Service Manual — part 21

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3. fault of pressure signal inputting port on
ECM

3. chane the ECM

Fault Code :P2128

fault code

P2128

high voltage of electronic accelerator pedal position sensor 2#
circuit

setting emergency control scheme

light up fault lamp until it is off

connection terminal

MT22.1

2 accelerator pedal
position sensor 2

normal measurement
signal

5V reference voltage

66

1

5V

2：accelerator pedal signal 2

42

6

0.5 ～ 4.5V

sensor signal ground

76

5

0V

judging criteria

possible fault reason

referenced trouble shooting scheme

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fault code

P2128

high voltage of electronic accelerator pedal
position sensor 2# circuit

engine is running

fault lasted for

more than 2.5

seconds

1. poor connecting

1. connect it again

2. sensor signal circuit is open

2. repair wiring harness

3. sensor signal circuit is short to ground

3. repair wiring harness

4. sensor damage

4. change the sensor

5. fault of this signal inputting port

5. change the ECM

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III、Electronic Throttle Valve

(I)Disassemly

1. Open the engine cover

2. Cut off the battery negative cable. Please refer to cut-off and connection of battery cables

3. Disassemble air filter a ssenmly. Please refer to air filter assembly

4. disassemble the electronic throttle valve

1). Cut off the wiring harness connection of electronic throttle valve.

2). Cut off the conection between electronic throttle
valve and air outlet pipe of air filter

3). Remove the four fixed bolts on electronic throttle

valve, and take out the valve from intake manifold.

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(II)Check

1. electronic throttle valve appearance check

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1). Check if the sensor’s harness connectors are well-

connected and firm; if the sensor is loosen up or fallen

off; if the appearance is ok or is there any crack trace.

Stir the valve block to see whether it rotate smoothly

or not. Check if there is too much carbon deposition

in throttle valve

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2. Check the circuit

1). turn off the ignition switch, unplug the harness connector at sensor end;

2). open the ignition switch, use digital multimeter to

measure every terminals of sensor harness

connector;

3). When you measure the power terminal of sensor,

please use 5V voltage as the standard. If the voltage

is different, that means there is fault in controlling

circuit or ECM, and you should do further test;

4). When you measure the grounding terminal of sensor, it should be in breakover with battery negative pole.
If it is not, please check the grounding circuit.

(III)Assembly

1. assemble the electronic throttle valve

1). Assemble the 4 fixing bolts of electronic throttle valve and tighten them.

2). Connect the electronic throttle valve an air filter outlet pipe assembly; then tighten the clamp.

3). Connect the electronic throttle valve harness connector.

2. Assemble the air filter assembly.

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3. Connect the cable of battery negative pole.

4. Close the engine cover.

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IV、Absolute pressure sensor

(I)Disassembly

1. Open the engine cover.

2. Cut off the cable of battery negative pole. Please refer to Cut-off and Connection of Battery Cable.

3. Remove the air filter assembly. Please refer to air filter assembly.

4. Disassemble the absolute pressure sensor.

1). Cut off the harness connector

of throttle valve sensor.

2). Remove one fixing
bolt.

3). Take out the absolute
pressure sensor.

(II)Check

1. Appearance check

1). Check if the sensor’s harness connectors are well-

connected and firm; if the sensor is loosen up or

fallen off; if the appearance is ok or is there any crack

trace. Check if the sensor inspection hole is plugged.

2. Circuit check

1). Turn off the ignition switch; unplug the harness connector at sensor end;

2). Open the ignition switch, use digital multimeter to

measure every terminals of sensor harness connector;

3). When you measure the power terminal of sensor,

please use 5V voltage as the standard. If the voltage

is different, that means there is fault in controlling

circuit or ECM, and you should do further test;

4). When you measure the grounding terminal of sensor, the resistance between the grounding terminal and
battery negative pole should be lower than 3Ω. If the resistance is abnormal, please check the grounding
circuit.

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5). If results of above checks are abnormal, please turn

off the ignition switch, plug out the ECM harness, and

check of the harness between sensor terminal and

ECM terminal is open or short-circuit.

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(III)Assembly

1. Assemble absolute pressure sensor

1). Assemble absolute pressure

sensor fixing bolts.

tightening torque 6±0.5N.m

2). Connect the harness connector
of absolute pressure sensor.

2. Assemble air filter assembly

3. Connect cable of battery negative
pole

4. Close the engine cover

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V、Water temperature sensor

(I)Disassembly

1. Open the engine cover

2. Cut off the cable of battery negative pole. Please refer to Cut-off and Connection of Battery Cable.

3. Drain off the coolant. Please refer to Change the Coolant.

4. Disassemble water temperature sensor

1). Cut off the harness connector of water temperature sensor.

2). Disassemble
water temperature
sensor.

3). Take out the
water temperature
sensor.

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(II)Check

1. Appearance check

1). Check if the sensor’s harness connectors are well-

connected and firm; if the sensor is loosen up or

fallen off; if the appearance is ok or is there any

crack trace.

2. Circuit check

1). Turn off the ignition switch; unplug the harness connector at sensor end;

2). Open the ignition switch, use digital multimeter to

measure every terminals of water temperature

sensor harness connector;

3). When you measure the power terminal of sensor,

please use 5V voltage as the standard. If the voltage

is different, that means there is fault in controlling

circuit or ECM, and you should do further test;

4). When you measure the grounding terminal of sensor, the resistance between the grounding terminal and
battery negative pole should be lower than 3Ω. If the resistance is abnormal, please check the grounding

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circuit.

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(III)Assembly

1. Assemble the water temperature sensor

1). On the occasion that the sealing ring of water

temperature sensor is in good condition, please

smear a little sealing glue on sensor thread and

sealing gasket; then assemble and tighten the water

temperature sensor.

tightening torque 20±4N·m

2).Connect the harness
connector of water
temperature sensor.

2. Check and fill the coolant to
proper level

3. Connect the cable of battery
negative pole

4. Close the engine cover

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VI、Camshaft position sensor

(I)Disassembly

1. Open the engine cover

2. Cut off the cable of battery negative pole. Please refer to Cut-off and Connection of Battery Cable.

3. Remove the air filter assembly. Please refer to air filter assembly.

4. Disassemble the camshaft positon sensor

1). Cut off the harness connector of

camshaft positon sensor.

2). Remove one fixing bolt of camshaft
positon sensor.

3). Take out the camshaft positon
sensor.

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(II)Check

1. Appearance check

1). Check if the sensor’s harness connectors are well-

connected and firm. And check if the distance

between Hall elements and signal wheel is accord with

the standard. Please also check if there is dirt or iron

filling between them, and clean them if it is.

2. Circuit check

1). Turn off the ignition switch; unplug the harness connector at sensor end;

2). Open the ignition switch, use digital multimeter to

measure every terminals of sensor harness connector;

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3). When you measure the power terminal of sensor,

please use 5V voltage as the standard. If the voltage

is different, that means there is fault in controlling

circuit or ECM, and you should do further test;

4). When you measure the grounding terminal of sensor,

it should be in breakover with battery negative pole.

If it is not, please check the grounding circuit.

5). If results of above checks are abnormal, please turn

off the ignition switch, plug out the ECM harness, and

check of the harness between sensor terminal and

ECM terminal is open or short-circuit.

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(III)Assembly

1. Assemble the camshaft positon sensor

1). Assemble the camshaft positon sensor on engine,

and tighten the fixing bolts.

tightening torque 9~11N·m

2). Connect the harness connector of
camshaft positon sensor.

2. Assemble air filter assembly

3. Connect the cable of battery negative
pole

4. Close the engine cover

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VII、Crankshaft position sensor

(I)Disassembly

1. Open the engine cover

2 .Cut off the cable of battery negative pole. Please refer to Cut-off and Connection of Battery Cable.

3. Remove the right front cover of engine. Please refer to Engine Front Cover.

4. Remove the dynamo belt. Pleasr refer to Dynamo Belt.

5. Remove the compressor assembly. Please refer to Compressor Assembly.

6. Disassemble the crankshaft position sensor

1). Cut off the harness connector of

crankshaft positon sensor.

2). Remove the fixing bolts of
cranshaft positon sensor.

3). Take out the crankshaft
positon sensor.

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(II)Check

1. Appearance check

1). Check if the sensor’s harness connectors are well-

connected and firm. And check if the distance

between Hall elements and signal wheel is accord with

the standard. Please also check if there is dirt or iron

filling between them, and clean them if it is.