Audio System - Speaker Noise When Using Auxiliary Device
Bulletin No: 09-003/09Last Issued: 06/24/2009
Subject:
NOISE FROM SPEAKERS WHEN USING AUX JACK AND 12V ACCESSORY SOCKET
BULLETIN NOTE
APPLICABLE MODEL(S)/VINS
2009 CX-7
2007-2008 CX-9
2007-2009 Mazda3
2008-2009 Mazda5
2009 RX-8
DESCRIPTION
Some customers may complain about noise from the speakers when using a portable audio device (such as an MP3 player) connected to the vehicle's audio system via the auxiliary (AUX) jack while powering the device (through the device's charger) using the vehicle's 12V accessory socket.
The symptom may occur when the engine is running and/or off (with ignition in ACC position). The symptom does not occur when the audio device is not connected to the 12V accessory socket through the charger.
The noise may be caused by one or more of the following:
^ Ground Loop Noise - A ground loop occurs when there is more than one ground connection path between two pieces of equipment. The duplicate ground paths form the equivalent of a loop antenna which very efficiently picks up interference that is transmitted as noise from the audio system. Additionally, any slight potential (voltage) differences between the grounds will cause current to flow from one to the other and add to the noise.
^ Charger Noise - The device's charger creates noise interference when connected to the 12V accessory socket and the device.
^ Vehicle Noise - Alternator and ignition noise may come into the audio line through the vehicles 12V power source.
Customers having this concern should have their vehicle repaired using the following repair procedure.
REPAIR PROCEDURE
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