Audio System - Audio Volume Fluctuation
91 Bose sound system volume fluctuates91 10 14
2010296/7
April 26, 2010
Supersedes Technical Service Bulletin Group 91 number 08-60 dated November 6, 2008 for reasons listed below.
Affected Vehicles
Condition
BOSE(R) sound system volume level is perceived to fluctuate by itself. This is likely to occur with louder ambient noise levels such as when driving on rough road surfaces or during hard acceleration.
Technical Background
The Audio Pilot(TM) dynamic noise compensation feature of the amplifier may be too aggressive, as volume adjustments are noticeable when cabin noise levels change.
Tip: Audio Pilot cannot be adjusted in the radio menu. The speed-controlled volume adjustment function, SVC, operates independently from Audio Pilot.
Production Solution
Optimized amplifier DSP (Digital Signal Processing) algorithm.
Service
To eliminate the radio volume level fluctuation, the Audio Pilot function can be disabled by modifying the electrical harness and enabling SVC, if necessary. Wiring repairs should be performed using the VAS 1978 Harness Repair kit.
Disabling Audio Pilot(TM) function
1. Remove necessary trim to access the amplifier and disconnect the wiring harness electrical connector.
2. Remove the electrical connector cover and insulating tape on harness to gain access to the wiring.
3. Locate the wire in cavity 6 of the electrical connector.
Tip: This wire is usually white, but in some models, the wire may be black. Check the appropriate wiring diagram if unsure.
4. Cut this wire approximately 2-1/2 inches from the connector,
leaving enough wire on both sides to install a butt connector.
5. Strip the insulation on both wire ends approximately 1/4 inch. Install blue butt connector (part number 111 971 939B) and crimp onto only the harness side of the wire.
6. Remove the inner hard-shell containing wire terminals 23 - 32 of the amplifier connector and release the wire lock by rotating outward.
7. Insert electrical terminal of repair wire (part number 000 979 025A) into the connector. Reassemble the inner and outer connector hardshells and connector cover.
On TT roadster vehicles, the wire is inserted into cavity 25 of the amplifier connector.
On all other vehicles, the wire is inserted into cavity 24 of the amplifier connector.
8. Route the repair wire to the open side of the butt connector. Cut the wire to length and strip the wire insulation approximately 1/4 inch.
9. Insert both the repair wire and the remaining white wire (connector side) into the butt connector and crimp.
10. Use Electric Hot Air Blower VAS 1978/14 and Adapter for Heat Gun VAS 1978/15 to shrink and seal butt connector. Tape exposed wiring.
11. Reassemble the electrical connector completely and reconnect to the amplifier.
Enabling Speed Volume Control (SVC)
Using the VAS Diagnostic tool, enable SVC by changing the adaptation channel.
Concert or Symphony radio:
1. Change the adaptation value to 0 by selecting: Vehicle Self Diagnosis >> 56 - Radio >> 012 Adaptation >> Channel 66 >> 0.
2. The speed-dependent volume increase can now be adjusted in five stages using the radio menu. The menu is accessed by pressing and holding the MENU button for 2 seconds.
Tip: On some 2003-2004 TT models, Adaptation Channel 66 will not be accessible. On these models, SVC is always available and cannot be removed from the radio menu.
Navigation plus (RNS-E) radio:
1. Change the adaptation value to 3 by selecting: Vehicle Self Diagnosis >> 56 - Radio >> 012 Adaptation >> Channel 8 >> 3.
2. The speed-dependent volume increase can now be adjusted in five stages using the DSP menu of the Navigation plus.
Warranty
Required Parts and Tools
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.