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

id0903e2817600

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
•  Audio amplifier malfunction (with Bose®)
•  Poor connection of audio unit connector, terminal damage
•  Poor connection of audio amplifier connector, terminal damage (with Bose®)
•  Antenna malfunction (e.g., poor ground)
•  Open or short circuit in wiring harness between audio amplifier and ground (with Bose®)
Note
•  AF 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 volume button 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 unit power to 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 the step 5.
4
•  Remove the after-market equipment.
•  Turn the audio unit power to 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 the 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
•  Turn the ignition switch to the LOCK position.
•  Remove the audio unit (without Bose®) or the audio amplifier (with Bose®).
•  Inspect the connection of the audio unit connector (without Bose®, 24-pin) or the audio amplifier connector (with Bose®, 16-pin) (for sound signal line).
•  Is the connector connected securely?
Yes
Go to the next step.
No
Repair or replace the terminal or connector. 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 the manual antenna.
•  Is the ground condition normal?
Yes
Repair or replace the manual antenna. Go to the next step.
No
Go to the next step.
11
•  Is there any noise?
Yes
Without Bose®
•  Replace the audio unit.
With Bose®
•  Replace the audio amplifier if any of the following occur:
―  The noise occurs from a specific speaker.
―  Noise occurs when the volume is minimized.
•  Replace the audio unit if any of the following occur:
―  The noise occurs from two or more speakers.
―  No noise occurs when the volume is minimized.
No
The system is normal.