Audio System Speaker Mechanical Diagnostics
Audio System Speaker Mechanical Diagnostics
Condition/Concern
Some customers may comment that the audio speaker sound quality is poor, has a buzzing sound or rattles while listening to the radio or other music source.
This condition may be caused by the trim, moldings or water deflectors located in the area of the speaker.
Recommendation/Instructions
1. Before beginning the diagnosis, determine the operating conditions that are contributing to the condition. Ask the customer the following questions:
* Determine the type of music the customer is listening to i.e. Rock, Country, Rap, Hip-Hop, etc.
* Which source was being used when the condition occurred i.e. FM, AM, CD, USB, Aux.
* When did the condition occur, only in the morning? After sitting in the sun?
* Determine the temperature of the vehicle when the condition occurs. Was is cold outside? Only after the vehicle heated up?
* What area of the vehicle did the noise come from?
* Was there anything else in the vehicle when the condition occurred? Packages? Loose items?
2. Check for any audio system related DTCs. If there are any DTC's, follow the appropriate diagnostic procedure.
3. Music CDs do not hold tone long enough to diagnose trim rattles. Obtain GM Test CD part number # J39916-CD (SPX, 1-800-345-2233). There may be certain audio frequencies such as bass that can cause buzz or rattle in the interior trim. Most trim rattles are caused by bass frequencies in the range of 50-80 Hz and are found on track 3.
4. Insert the GM Test CD and play various tracks corresponding to the type of music the customer was listening to when the condition occurred and verify the condition.
5. Hold the volume at a constant level and use the balance and fader controls to isolate the speaker(s) that are experiencing the condition.
6. Apply hand pressure to the trim in the area of concern.
7. If the sound changes when the trim is depressed or manipulated by hand, then the trim is causing the rattle or buzz.
Loose Trim, Panel to Panel Contact
An interface may cause a rattle or buzz. For example, between a door and instrument panel.
* To better identify the location, open the door and determine if the buzz or rattle follows the door. This may be caused by loose door trim or water deflector contact with the trim. Refer to Door Trim/Water Deflector Rattle below.
* Determine if a rattle is heard between the instrument panel and door. This may be caused by contact between the instrument panel and the door trim when the door is closed. If the noise goes away when the door is opened, inspect the trim panel on the door to ensure it is in the correct position. Also, inspect the snap-on trim panels on the instrument panel ends to ensure they are fully engaged into the instrument panel.
* If the rattle or buzz is determined to be coming from the instrument panel, inspect for loose panels, screw covers or contact between trim panels such as an A pillar to instrument panel interference.
Door Trim/Water Deflector Rattle
If the rattle is heard within the door trim, depress the trim with your hand. If the sound changes or the rattle/buzz decreases when pressure is applied, preform the following steps:
1. Remove the door trim screw cover behind the door handle on the affected door and apply pressure to the water deflector. If this cures the condition, proceed to the step 3.
2. Once the door trim is removed, confirm the perimeter clips are not damaged, bent or missing. Replace damaged door clips. Add flocking tape as needed.
Note: The foam shipping blocks installed on new vehicle door edges can be used to compress the water deflector.
3. If the rattle is caused by the water deflector, install two 100 mm (4 in) long layers of 1" x 9/16" adhesive backed foam shim stock, or equivalent, to compress the water deflector as shown. Confirm any added foam does not interfere with the window or door lock operation.
4. Reinstall all components and verify the condition is corrected using the same audio source that created the condition.