Audio Systems: GMC Truck speakers not working properly, truck speakers, gmc sierra

Question
Tom,

    Now that I think about it, I do remember on a recent trip to Dallas that I went over a patch of bumpy spots on the road and that the speaker in the passenger side door come back on. Is this a repairable problem or does the stereo need to be replaced. It's factory so I suppose it wouldn't be a big loss, just kinda sucks that it is barely two years old and is acting up. Thanks!
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Followup To
Question -
I have a 2002 GMC Sierra 1500 extended cab truck. The speaker in the front passenger side door currently doesn't work. It started to come in and out about a month ago and now it has quite working completely. Also, the front speaker on the driver's side sometimes sounds like it's talking "underwater". Have any ideas on what is going on?
Answer -
Hello Chuck,
It's possible that the stereo has defective solder connections on the audio output modules. This vehicle may also use seperate amps at each speaker and they are failing. You may want to try the tap test, with the stereo on use a screw driver and lightly tap on the case of the stereo to see if this will make the sound return. If tapping on the stereo case and the sound returns then you will know that a defective connection/s is the problem.

TOM,
T&D  ELECTRONICS
tdeser@zoominternet.net

Answer
Chuck,
It sounds like two possible problems may be the cause of the sound going in and out. 1-defective solder connections on the pins of the amplifiers inside the stereo. 2-defective wire connections between the stereo and the speakers. In many cases I simply resolder the connections on the amp IC's and the stereo will work as good as new.

TOM,
T&D ELECTRONICS