NO.1 AF NOISE OR POP NOISE AT ALL SOURCES (RADIO, CD) [AUDIO]

id0903e1817600

1

AF noise or POP noise at all sources (Radio, CD)

Possible DTC

09:Er20, 09:Er21
Possible cause
•  Low vehicle battery voltage.
•  Jammed radio signals from after market equipment.
•  Speaker malfunction (e.g., foreign material penetration, damage)
•  Improper speaker installation
•  Audio unit malfunction
•  Poor connection of audio unit connector, terminal damage
•  Antenna malfunction (e.g., poor ground)
Note
•  AF (audio frequency) noise is a snapping noise that generally occurs during ON/OFF switching operations of electrical equipment other than the audio unit, or a continual rasping noise that occurs when electrical equipment is operated. This is caused by noise interference in the power supply wiring, signal wiring, speaker cable or head of cassette deck. Therefore noise can be heard regardless of radio wave conditions or the audio volume position. The noise will start after one click from the minimum position of the POWER/VOLUME switch but normally does not change even when volume is turned to a higher position.
•  POP noise is snapping or popping noise that occurs during ON/OFF switching operation of the audio unit, or when switching from radio to CD. Even a normal audio unit sometimes emits a little noise depending on the conditions.

Diagnostic procedure

STEP

INSPECTION

ACTION
1
•  Inspect the vehicle battery voltage.
•  Is the vehicle battery voltage normal?
Specification:
Ignition switch ON: 11.5 V or more
Idle: 12.5 V or more
Yes
Go to the next step.
No
Charge the battery, then go to the next step.
2
•  Turn the audio system on.
•  Is there any noise?
Yes
Go to the next step.
No
The system is normal. Explain to the customer that the vehicle battery voltage was low.
3
•  Are any of the following after-market equipment installed? (Inspect especially near the antenna.)
―  Radar detector
―  Remote engine starter
―  Anti-theft device
―  Other
Yes
Go to the next step.
No
Go to Step 5.
4
•  Remove the after-market equipment.
•  Turn the audio system on.
•  Is there any noise?
Yes
Go to the next step.
No
The system is normal. The after-market electrical devices might be the cause of the noise.
5
•  Is there noise coming from all the speakers?
Yes
Go to Step 7.
No
Go to the next step.
6
•  Inspect the suspect speaker.
•  Is the speaker normal?
Yes
Go to the next step.
No
If there is any foreign material adhering to the speaker:
•  Remove the foreign material from the speaker.
If the speaker is malfunctioning:
•  Replace the speaker.
If the speaker is not installed properly:
•  Install the speaker properly.
7
•  Attempt to duplicate the symptom on another vehicle.
•  Does the noise level improve compared to the customer’s vehicle?
Yes
Go to the next step.
No
The system is normal. Explain the noise generation mechanism to the customer.
Note
•  The noise level that may be heard varies depending on the operating speed of the audio power and/or mode switches.
8
•  Remove the center panel unit.
•  Inspect the connection of the audio unit connector (24-pin).
•  Disconnect the audio unit connector and inspect both the audio unit and the wiring harness-side connectors for a poor connection. (such as damaged/pulled-out pins, corrosion).
•  Are all the pins normal?
Yes
Go to the next step.
No
If poor connection of audio unit connector:
•  Securely connect the audio unit connector.
If the audio unit side connector is malfunctioning:
•  Replace the audio unit.
If the wiring harness-side connector is malfunctioning:
•  Repair or replace the pins and/or the connector.
After treating either the above-mentioned, then go to the next step.
9
•  Is there any noise?
Yes
Go to the next step.
No
The system is normal.
10
•  Inspect the ground condition of manual antenna.
•  Is the ground condition normal?
Yes
Go to the next step.
No
Repair or replace the ground. Go to the next step.
11
•  Is there any noise?
Yes
•  Replace the audio unit.
No
The system is normal.