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

id0903e2817600

1

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

Possible DTC

With M-MDS

U3000:09

Without M-MDS
Audio unit
•  09:Er21
Car-navigation unit
•  Device code 09/Error code 21
POSSIBLECAUSE
•  Low vehicle battery voltage.
•  Jammed radio signals from after market equipment.
•  Speaker malfunction (e.g., any foreign material, broken)
•  Improper speaker installation
•  Audio unit malfunction (with audio system)
•  Car-navigation unit malfunction (with car-navigation system)
•  Poor connection of audio unit connector, terminal damage (with audio system)
•  Poor connection of car-navigation unit connector, terminal damage (with car-navigation system)
•  Poor connection of audio amplifier connector, terminal damage (with Bose®)
•  Antenna malfunction (e.g., poor ground)
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:
Switch the ignition to 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 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
•  Is any of the following after-market equipment installed? (Inspect especially near the antenna.)
―  Radar
―  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 to ON.
•  Is there any noise?
Yes
Go to the next step.
No
The system is normal. The after-market electrical devices might make a noise.
5
•  Is there the noise from all 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 on 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 the other vehicle.
•  Is the noise better than 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 may be heard depends on the operating speed of audio power and/or mode switch.
8
•  Switch the ignition to off.
•  Remove the audio unit.
•  Inspect the connection of the audio unit/car-navigation unit connector (24-pin) (for sound signal line).
•  Is the connector connected securely?
Yes
Go to the next step.
No
If poor connection of audio unit/car-navigation unit connector:
•  Securely connect the audio unit connector.
If the audio unit/car-navigation unit side connector is wrong:
•  Replace the audio unit (with audio system).
•  Replace the car-navigation unit (with car-navigation system).
If the wiring harness-side connector is wrong:
•   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 the 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
Without Bose®:
•  Replace the audio unit (with audio system).
•  Replace the car-navigation unit (with car-navigation system).
With Bose®:
•  If noise occurs from the speaker of a specific channel, or the volume is minimized and the noise occurs:
―  Replace the audio amplifier.
•  If noise occurs from the speaker of two or more channels or the volume is minimized and the noise dose not occurs:
―  Replace the audio unit (with audio system).
―  Replace the car-navigation unit (with car-navigation system).
No
The system is normal.