Interior - Rear Shelf Audio Induced Buzzing Noise
TECHNICALBulletin No.: 09-08-44-003
Date: February 18, 2009
Subject:
Rear Window Shelf Audio-Induced Buzz, Squeak or Rattle Noises (R & R Rear Window Trim Panel, Install Flocking Tape and Shim Stock)
Models:
2008-2009 Cadillac CTS, CTS-V
Condition
Some customers may comment on hearing a buzz, squeak, or rattle noise coming from the area of the rear speakers.
Cause
The condition may be caused from components mounted on the rear window shelf and rear window panel support brackets reacting to the acoustic output of the rear speakers.
Correction
Important:
If your diagnosis leads you to consider replacement of any of the rear shelf-mounted speakers (10" subwoofer or 80 mm speaker), the following steps MUST be completed prior to the replacement of the speaker.
The following steps have been identified to eliminate these buzz, squeak, or rattle conditions. They are listed in order of highest probability of resolving the issue. All of the conditions should be confirmed with the use of an audio CD as described below.
Note
The use of an audio CD with "test tones," such as sine sweeps in the 20-160Hz range, will help identify these squeak, buzz, and rattle conditions. Other bass heavy content can serve as a substitute if a squeak and rattle CD is unavailable. Other acceptable audio material includes:
^ Music which the customer has indicated causes the concern.
^ GM Squeak and Rattle Audio CD / GMN3851TP (tracks 11-14) / TX155172A (tracks 6-8)
Tip
Prior to removing the rear window trim panel assembly, look for evidence of the following:
^ Look down through the rear window to see if any of the trim panel's white underside insulation (1) is partially covering the opening in the speaker grille. Areas of the insulation can come loose and create a buzz/rattle noise by contacting a moving area of the speaker.
^ Holding the trim panel down at the rear edge near the window will quiet a trim panel to sheet metal issue; holding the trim panel down at the front edge near the child seat anchor will quiet a trim panel to bracket issue.
Inspect the rear window trim panel for possible vibration against the rear shelf sheet metal and/or rear window panel support brackets, creating a buzz/rattle condition. Remove the rear window trim panel assembly, following SI, and complete the following procedures:
^ Add/replace flocking tape to the underside of the trim panel at the nine rear edge contact points shown above. Use Kent Automotive Flocking Tape, P/N KT13486, or equivalent.
^ Add/replace flocking tape to the standoffs (1) on the rear window panel support bracket, which are two places where the bracket contacts the rear window trim panel.
^ Inspect the rear window trim panel underside insulation to ensure it is securely attached to the trim panel. Use spray adhesive (1) to re-secure any areas that have become detached.
Note
Removal of the component(s) from the rear window panel support brackets will temporarily quiet the condition below.
1. If present, inspect the rear shelf OnStar(R) module, the rear object sensor control module, and the remote control door lock receiver for possible vibration against the rear window panel support brackets, creating a buzz/rattle condition. Add adhesive backed shim stock (1) to the underside of the component(s) and reinstall to the rear window panel support brackets. Use Kent Automotive Shim Stock, P/N 46475, or equivalent.
2. Inspect the rear subwoofer for possible vibration against the rear window panel support bracket, creating a buzz/rattle condition. Verify that all screws securing the subwoofer to the bracket are fully driven, seated and not stripped. In most cases, the vibration will now be eliminated and you can move ahead to Step 4. However, if a vibration is still evident, proceed with the following steps:
Tip
Verify that the gasket (1) on the underside of the subwoofer is providing cushion between the subwoofer and the support bracket. Listen for an air leak between the speaker and bracket, pushing down on the subwoofer between mounting points, if needed.
1. If the cushioning appears to be insufficient, remove the rear subwoofer from the support bracket.
2. Add shim stock (1) to the underside of the subwoofer, inboard of the gasket. Use Kent Automotive Shim Stock, P/N 46485, or equivalent.
3. Reinstall the rear subwoofer to the support bracket.
Note
The rear window panel support brackets have some irregular shapes that extend a distance from their mounting points, as noted in the graphic above. These types of areas may be prone to vibration against the rear shelf sheet metal. Test for areas of vibration by pushing down on the bracket while playing the audio CD. The areas, when pushed, which cause the buzz to stop should be targeted for the addition of the shim stock.
3. Inspect the rear window panel support brackets for possible vibration against the rear shelf sheet metal, creating a buzz/rattle condition. Add Kent Automotive Shim Stock, P/N 46475, or equivalent, between the rear window panel support bracket and the rear shelf sheet metal.
4. Reinstall the rear window trim panel following the procedures in SI.
Parts Information
Warranty Information
Disclaimer