146
Audio System - Rattling/Humming Noise From Speakers
91 Sound system: interference
91 11 20
2018187/6
October 21, 2011.
Supersedes Technical Service Bulletin Group 91 number 10 - 55 dated August 20, 2010 for reasons listed below.
Affected Vehicles
Condition
Cracking, grinding, rattling, humming or similar interference from one or more loudspeakers.
Technical Background
Parts of the interior fittings such as door covers, rear shelf, facings or covers can be made to vibrate at certain frequencies and then cause noises. It is
possible that loudspeaker brackets, cables or covers can be made to vibrate.
Production Solution
Not Applicable.
Service
1. Verify if interferences come from loose objects (such as keys, CD covers, pens, sunglasses, etc.) in the vehicle. If the interference is not coming
from loose objects, proceed to 2.
2. Verify if interferences disappear when the trim surrounding the speaker is pushed against the speaker or the speaker against its mounting. If the
interference does not disappear with pressure, proceed to 3.
3. Remove loudspeaker from its mounting and listen to the loudspeaker outside of vehicle. If the sound from the speaker does not exhibit the
concern, then do not replace the loudspeaker and proceed to 4.
4. Check if interferences come from parts of the cabin fittings. Loose parts should be fixed, an underlay applied, or, if necessary, replaced.
147
Warranty
Additional Information
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service
manuals for the latest information.
