Audio System Sound Quality Diagnosis

Audio System Sound Quality Diagnosis

Special Tools Required

- Diagnostic CD 07AAZ-SDBA100

Use the following tests to check sound quality.

NOTE: Before beginning the following tests, write down the bass, treble, fader and balance settings, and then set them to their center positions for testing.

Left/Right Channel ID

Do this test to confirm proper channel routing.

1. Insert the diagnostic CD (T/N: 07AAZ-SDBA100) into the audio-navigation unit or the audio unit.

2. Play track No. 1 (left, both, right channel ID) at a normal, or slightly higher than normal, volume level.

3. The voice should be audible only from the channel or channels when indicated.

- If the channel ID is correct for each side, go to Phase Test.
- If the channel ID is not correct, check for;
- Shorted speaker wire
- Faulty stereo amplifier
- Faulty audio-navigation unit or audio unit

Phase Test

Do this test to confirm proper speaker phasing.

1. Insert the diagnostics CD (T/N: 07AAZ-SDBA100) into the audio-navigation unit or the audio unit.

2. Play track No. 2 (phase) at a normal, or slightly higher than normal, volume level.

3. The voice should sound centered and focused when it is in-phase.

4. The voice should sound diffused, and have less bass when it is out of phase.

- If the voice changes from in-phase to out of phase as indicated by the prompt, the phasing is correct. Go to Electrical Noise Test.
- If the voice always sounds out of phase, phasing is not correct. Check for;
- Crossed speaker wires
- Faulty stereo amplifier
- Faulty audio-navigation unit or audio unit

Electrical Noise Test

Do this test to check for electrical noise being induced into the audio system.

NOTE: Electrical noise may be caused by outside sources that cannot be handled by the audio system. Make sure you remove any cell phones and/or turn off any aftermarket devices before beginning this test.

1. Insert the diagnostic CD (T/N: 07AAZ-SDBA100) into the audio-navigation unit or the audio unit.

2. Play track No. 4 (digital zero) at a normal, or slightly higher than normal, volume level.

3. Operate any electrical device that may create electrical noise in the audio system, including starting the engine.

4. Play track No. 5 (near digital zero) at a normal, or slightly higher than normal, volume level.

5. Operate any electrical device that may create electrical noise in the audio system, including starting the engine.

6. Play track No. 6 (SNR) at a normal, or slightly higher than normal, volume level.

7. Operate any electrical device that may create electrical noise in the audio system, including starting the engine.

- If no abnormal noise is heard, go to Individual Speaker Test.
- If the noise is present only during the SNR track, replace the audio-navigation unit or audio unit.
- If the noise is heard during the digital zero or near digital zero track, check for;
- Poor ground for the audio unit, amplifier, engine or battery cable
- Pinched or shorted speaker or amplifier wire
- Faulty stereo amplifier
- Faulty audio-navigation unit or audio unit
- Other faulty components causing excessive electrical noise (ignition coils, alternator, door lock actuators, etc.). Disconnect any suspect components, and then replay the tracks that were originally noisy. If the noise is gone, check the component's circuit and the component.

Individual Speaker Test

Do this test to identify a faulty speaker.

1. Insert the diagnostic CD (T/N: 07AAZ-SDBA100) into the audio-navigation unit or the audio unit.

2. Play track No. 30 (steady 300 Hz tone) at a normal, or slightly higher than normal, volume level.

3. Listen to each speaker for poor sound compared to the other speakers. Use the audio system's fader and balance settings to help isolate the channel with the problem.

- If the sound quality produced by a specific speaker is poor, substitute it with a known-good speaker. If the poor sound quality continues, go to Sound Balance Test.
- If the sound quality is OK, go to Sound Balance Test.

Sound Balance Test

Perform this test to identify a faulty channel or speaker.

1. Insert the diagnostic CD (T/N: 07AAZ-SDBA100) into the audio-navigation unit or the audio unit.

2. Confirm the bass and treble are set to the center positions.

3. Play track No. 3 (pink noise) at a normal, or slightly higher then normal, volume level.

4. A static type sound should be heard through all speakers.

5. Insert the audio diagnostic CD (T/N: 07AAZ-SDBA100) into the audio-navigation unit or the audio unit of a known-good vehicle.

6. Set the bass and treble to the center position.

7. Play track No. 3 (pink noise) at the same level that was played in step 3.

8. Compare the sounds made by the two vehicles.

- If the noise sounds made by the two vehicles are very similar, go to Frequency Sweep Test.
- If the sound does not have as much bass, check the subwoofer and circuit.
- If the sound does not have enough hiss, check the tweeters and their circuits.

Frequency sweep

Do this test to find rattles or reverberation that may cause a perception of poor sound quality.

1. Insert the diagnostic CD (T/N: 07AAZ-SDBA100) into the audio-navigation unit or the audio unit.

2. Play track No. 13 (sweep from 500 Hz to 35 Hz) at a normal, or slightly higher than normal, volume level.

3. Listen to each speaker for poor sound quality or reverberations caused by specific frequencies. Use the voice-over to estimate the frequency that causes the vibration. Use the audio system's fader and balance settings to help isolate the channel with the problem.

- If you hear vibrations or poor sound quality, go to step 4.
- If you do not hear any vibrations or poor sound quality, go to Sound Judging.

4. Choose the appropriate track from No. 14 to 25 (small range frequency sweep) or 26 to 53 (single frequencies) to recreate the frequency that caused the poor sound quality or vibration located in step 3: this aids in diagnosis of the problem.

NOTE: When you get to the track that recreates the problem, select the repeat function on the audio system, this will help you isolate the cause.

5. Replace or insulate the source of the vibrations or, if the speaker is the source of the poor sound quality, replace it.

Sound judging

- Do this test to compare overall sound quality, imaging, and dynamics between the customer's vehicle and a known-good vehicle. Only use a vehicle of the same model and trim level for this test.
- Make sure the vehicle is using only OEM speakers.

1. In the customer's vehicle, set the bass, treble, fader, and balance settings to the customer's normal settings that were written down before beginning testing.

2. Insert the diagnostic CD (T/N: 07AAZ-SDBA100) into the audio-navigation unit or the audio unit.

3. Play tracks No. 7 to 12 (sound quality, midland, dynamics, and imaging demonstration tracks) at a normal, or slightly higher than normal, volume level. Write down the volume setting.

4. Listen to areas of the track that stand out as being either very clear, or poorer than other areas of the track.

5. Insert the diagnostic CD (T/N: 07AAZ-SDBA100) into the audio-navigation unit or the audio unit of a known-good vehicle.

6. Play the tracks at the same volume level and the same bass, treble, balance, and fader settings as used in step 3 in the customer's vehicle.

7. Listen to the same area of the track that stood out as being either very clear or poorer than other areas of the track.

8. Compare the customer's vehicle's sound quality results to the known-good vehicle's results.

- If the sound quality in the customer's vehicle is comparable to the sound quality in the known-good vehicle, then the customer's vehicle is operating as designed.
- If the sound quality is not comparable, check these items in order.
- Loose or improperly installed speakers or other hardware that may become excited by the vibrations generated by the speakers
- Poor power or ground to the stereo amplifier
- Damaged speaker(s)
- Faulty stereo amplifier
- Faulty audio-navigation unit or audio unit

Seek Stop Test

Do this test to check the performance of the audio system's AM and FM reception. Refer to symptom troubleshooting: Audio sound weak or distorted, or No sound is heard from the speakers (display is normal); with navigation Audio Unit Power Switch Will Not Turn On (No Information Display And No Sound) (With Navigation), without navigation Audio Unit Power Switch Will Not Turn On (No Information Display And No Sound) (Without Navigation) before continuing with this test.

NOTE:

- Window tint, aftermarket theft-recovery devices and other aftermarket accessories may reduce radio reception.
- Changes in cloud cover and other atmosphere conditions affect the ability of the audio system to receive radio signals.

1. Park the customer's vehicle in an open area away from buildings or other obstructions.

2. Park a known-good vehicle (same year, model, and trim level) next to the customer's vehicle, facing the same direction.

3. Start the engine in the customer's vehicle, and turn on the radio.

4. Set the FM receiver to 87.7 MHz.

5. Press the Seek + button and record the first station that the audio-navigation unit or the audio unit locks onto.

6. Press the Seek + button repeatedly, and write down each station that the audio-navigation unit or the audio unit locks onto until the station recorded in step 5is reached again.

7. Set the AM receiver to 530 kHz.

8. Press the Seek + button, and record the first station that the audio-navigation unit or the audio unit locks on to.

9. Press the Seek + button repeatedly, and write down each station that the audio-navigation unit or the audio unit locks onto until the station recorded in step 8is reached again.

10. Turn the ignition switch to LOCK (0).

11. Start the engine in the known-good vehicle, and then perform steps 4 thru 10 on the known-good vehicle.

12. Compare the number of stations received in steps 6 and 9 in the customer's vehicle with the number of stations received in the known-good vehicle.

- If the number of stations received is the same, or within 10 %, the audio-navigation unit's or audio unit's tuner performance is OK. The problem may be atmospheric conditions, multi path interference, or other obstructions to the radio signal.
- If the customer's vehicle receives fewer stations by at least 10 %, go to step 2 of Poor AM or FM radio reception of interference troubleshooting; with navigation Symptom Troubleshooting, without navigation Poor AM Or FM Radio Reception Or Interference (Without Navigation With XM Radio) before continuing with this test.