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Engine JAC HFC4DA1-2C. Manual - part 91

HO HORN

HORN

- 153 -

Diagnosis

Diagnosis and

and

and Testing

Testing

Troubleshooting

Horn always on.

Step

Operation

Yes

Is the vehicle equipped with any anti-theft system?

Go to Step 2.

Go to Step 3.

Is the vehicle diagnostic system check performed?

Go to Step 4.

Check vehicle

diagnostic system.

Is horn operation and other necessary inspection performed?

Go to Step 4.

Check horn harness.

Press and then release the horn botton.

Is the horn always on?

Go to Step 5.

Check horn harness.

Is the vehicle equipped with any anti-theft system?

Go to Step 6.

Go to Step 7.

Disconnect the body control module.

Is the horn always on?

Go to Step 7.

Go to Step 11.

Disconnect the horn relay.

Is the horn always on?

Go to Step 10.

Go to Step 9.

Check horn relay for poor contact. Is any fault detected and elimilated?

Go to Step 15.

Go to Step 14.

Repair the horn relay control circuit that is shorted to ground.

Is the maintenance finished?

Go to Step 15.

—

Check harness connector of body control module for poor contact.

Is any fault detected and elimilated?

Go to Step 15.

Go to Step 13.

Repair the shorted horn control circuit.

Is the maintenance finished?

Go to Step 15.

—

Replace the body control module.

Is the replacement finished?

Go to Step 15.

—

Replace the horn relay.

Is the replacement finished?

Go to Step 15.

—

Is the horn able to operate normally?

System is normal.

Go to Step 1.

HO HORN

HORN

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Diagnosis

Diagnosis and

and

and Testing

Testing

Troubleshooting

Horn failed to work.

Step

Operation

Yes

Is the vehicle equipped with any anti-theft system?

Go to Step 2.

Go to Step 3.

Is the vehicle diagnostic system check performed?

Go to Step 4.

Check vehicle

diagnostic system.

Is horn operation and other necessary inspection performed?

Go to Step 4.

Check horn harness.

Press and then release the horn botton.
Is the horn always on?

Check horn harness.

Go to Step 5.

1. Disconnect the horn relay.
2. Connect a test lamp between the positive battery voltage circuit of horn

relay coil and a sound ground.

Is the test lamp lit?

Go to Step 6.

Go to Step 13.

1. Connect a test lamp between the positive battery voltage circuit of horn

relay coil and the horn relay control circuit.

2. Press the horn button and hold it.
Is the test lamp lit?

Go to Step 7.

Go to Step 14.

Connect a test lamp between the positive battery voltage circuit of horn
relay button and a sound ground.
Is the test lamp lit?

Go to Step 8.

Go to Step 15.

Connect a jumper with a 15A fuse between the positive battery voltage
circuit of horn relay button and the horn control circuit.
Does the horn ring?

Go to Step 11.

Go to Step 9.

1. Reconnect the horn relay.
2. Disconnect the horn connector.
3. Connect a test lamp between the horn control circuit and a sound

ground.

4. Press the horn button and hold it.
Is the test lamp lit?

Go to Step 10.

Go to Step 16.

1. Connect a test lamp between the horn control circuit and the horn

ground circuit.

2. Press the horn button and hold it.
Is the test lamp lit?

Go to Step 12.

Go to Step 17.

Perform troubleshooting for the high impedence in the horn control circuit
or horn ground circuit.
Is the maintenance finished?

Go to Step 19.

—

Perform troubleshooting for the open circuit or high impedence in the
positive battery voltage circuit of horn relay coil.
Is the maintenance finished?

Go to Step 19.

—

Perform troubleshooting for the open circuit in horn relay control circuit or
shorted positive battery circuit. Horn relay control circuit is composed of
horn slip ring and horn button.
Is the maintenance finished?

Go to Step 19.

—

Perform troubleshooting for the open circuit or high impedence in the
positive battery voltage circuit of horn relay button.
Is the maintenance finished?

Go to Step 19.

—

Perform troubleshooting for the open circuit or high impedence in the horn
control circuit.
Is the maintenance finished?

Go to Step 19.

—

Perform troubleshooting for the open circuit or high impedence in the horn
ground circuit.
Is the maintenance finished?

Go to Step 19.

—

Replace the horn relay.
Is the replacement finished?

Go to Step 19.

—

Operate the horn.
Is the horn able to operate normally?

System is normal.

Go to Step 1

HO HORN

HORN

- 155 -

Diagnosis

Diagnosis and

and

and Testing

Testing

Troubleshooting

Inferior tone quality of horn.

Step

Operation

Yes

Is the vehicle equipped with any anti-theft system?

Go to Step 2.

Go to Step 3.

Is the vehicle diagnostic system check performed?

Go to Step 4.

Check vehicle

diagnostic system.

Is horn operation and other necessary inspection performed?

Go to Step 2.

Check horn harness.

Press the horn button.

Is there any screak or buzz?

Go to Step 5.

Check horn harness.

1. Check the horn for proper mounting torque.

2. Check if there is any fragment at the connecting part between horn and

vehicle.

Is any fault detected and elimilated?

Go to Step 9.

Go to Step 6.

Perform procedures below for each horn:

1. Disconnect the horn connector.

2. Connect a jumper with a 15A fuse between the positive battery terminal

of horn and the control circuit of horn.

3. Connect aother jumper between the negative battery terminal of horn

and the grounding terminal of horn.

Is there any screak or buzz?

Go to Step 8.

Go to Step 7.

Perform troubleshooting for the high impedence in the horn control circuit
or the horn ground circuit.

Is the maintenance finished?

Go to Step 9.

—

Replace the horn.

Is the replacement finished?

Go to Step 9.

—

Operate the horn.

Is the horn able to operate normally?

System is normal.

Go to Step 1

HO HORN

HORN

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Removal/Installation

Removal

Removal of

of horn

horn

Disconnect the negative cable of battery.

Remove the front bumper.

Remove the mounting bolt of horn and disconnect
the horn plug.

Remove the horn.

Content .. 89 90 91 92 ..