DEFINITION: Use this diagnostic table in order to diagnose EMI interference in the raio/audio system.

1. Verify the customer's complaint.
2. Identify the problem.

Is the vehicle equipped with aftermarket items such as a radar detector, cellular telephone or 2-way radio?

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Go to Step 4

Go to Step 3

Remove each component one at a time and notice if the noises go away with each component that has been removed.

Has the problem been identified with a component that has been removed?

--

Go to Step 3

Go to Step 4

1. Verify that the installation procedures for each aftermarket item conforms to the auto manufacturer's installation guidelines.
2. Properly install each item if the item does not conform to the auto manufacturer's installation gudelines.

Has the original problem been corrected?

--

System OK

Go to Step 4

1. Gather as much information on the problem as possible.
2. Verify if the noises are there with the engine running or not running or if the noises are intermittent or constant.

Is there a service bulletin for the problem?

--

Go to Step 5

Go to Step 6

Perform the service bulletin.

Has the problem been corrected?

--

System OK

Go to Step 6

1. Check the integrity of the ignition system.
2. Also check the integrity of the charging system.

Has the problem with the ignition system or with the charging system been found and corrected?

--

System OK

Go to Step 7

1. Identify all of the EMI components.
2. Remove each component one at a time and notice if the noises go away with each component that has been removed.

Has the problem been identified with a component that has been removed?

--

Go to Step 8

Go to Step 9

Replace the suspected faulty component.

Has the original problem been resolved?

--

System OK

Go to Step 9

1. Inspect all of the associated circuitry for all of the EMI components.
2. Also inspect the grounds and the harness connectors for all of the EMI components.

Is there a problem with any of the EMI component grounds or the harness connectors?

--

Go to Step 10

Go to Step 11

1. Repair the ground circuits for all of the associated EMI components.
2. Also repair the harness connectors if they are damaged or corroded for all of the associated EMI components.

Has the original problem been resolved?

--

System OK

Go to Step 11

Contact the auto manufacturer's technical assistance center for further assistance.

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DEFINITION: This table is used to resolve noise complaints that enter by coupling the audio lines.

1. With the radio OFF, temporarily interchange the audio output leads of the noisy speaker with those of a speaker that is not noisy at the amplifier connector.
2. Turn the radio ON.

Does the noisy speaker now perform without noise?

--

Go to Step 2

Go to Step 11

1. Verify that the audio leads were making good contact with the amplifier and the speaker.
2. Clean and repair the connectors if necessary.

Is the original problem resolved?

--

System OK

Go to Step 3

1. Turn the radio OFF.
2. Temporarily interchange the audio input leads from the sound processor interface to the amplifier (if equipped) of the noisy channel with those of a channel that are not noisy at the amplifier connector.

Does the noisy speaker now perform without noise?

--

Go to Step 5

Go to Step 4

Replace the amplifier with a known good amplifier.

Is the original problem resolved?

--

System OK

Go to Step 14

1. Verify that the audio leads were making good contact with the sound processor interface and the amplifier.
2. Clean and repair the connectors if necessary.

Is the original problem resolved?

--

System OK

Go to Step 6

1. Check all of the audio harness shields for a good ground connection.
2. Verify the good ground with the DMM to the negative battery post.
3. Repair the harness shields as necessary.

Is the original problem resolved?

--

System OK

Go to Step 7

Install a set of temporary audio leads from the sound processor interface to the amplifier.

Is the original problem resolved?

--

Go to Step 8

Go to Step 9

1. Install a new set of audio leads from the sound processor interface and the amplifier.
2. Route the new leads away from the existing leads.

Is the replacement complete?

--

System OK

--

Replace the sound processor interface with a known good model.

Is the original problem resolved?

--

System OK

Go to Step 10

Replace the radio with a known good radio.

Is the original problem resolved?

--

System OK

Go to Step 14

Install a set of temporarily audio leads from the amplifier to the noisy speaker.

Is the original problem resolved?

--

Go to Step 12

Go to Step 13

1. Install a new set of audio leads from the amplifier to the noisy speaker.
2. Route the new leads away from the existing leads.

Is the replacement complete?

--

System OK

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1. Verify that the audio leads are making good contact with the speaker and the amplifier.
2. Clean and/or repair the connections as needed.

Is the original problem resolved?

--

System OK

Go to Step 14

Contact the auto manufacturer's technical assistance center for further assistance.

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Was the EMI Troubleshooting Guide performed?

--

Go to Step 2

Go to Speaker Noise - Accessory .

Use a charging system tester or oscilloscope to check for excessive ripple in the output voltage of the alternator with the engine running and the charging system under load.

Is there excessive ripple present?

--

Go to Step 3

Go to Step 4

Replace the alternator. Refer to Generator Replacement in Engine Electrical.

Did the noise go away?

--

System OK

Go to Step 5

1. Inspect all connections at the battery.
2. Verify that all connections are clean, tight and not corroded.
3. Check all engine grounds, including the ground wire from the negative battery terminal to the chassis.
4. Verify all ground connections with the DMM.
5. Make sure that all ground connections are clean and tight.
6. Check the alternator connections.
7. Clean and repair all corroded connections.

Did the noise go away?

--

System OK

Go to Step 5

1. Gather as much information on the problem as possible.
2. Locate and perform any service bulletin that may exist for this particular problem.

Did the noise go away?

--

System OK

Go to Step 6

Contact the auto manufacturer's technical assistance center for further assistance.

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