Buzz coming from right rear passenger door speaker. Can't solve.

I have a 2005 Tahoe with a buzz coming from the Bose speaker in the right rear passenger door when the radio is on. The pitch of the buzz increases with engine RPMs. The dealer said our speaker was bad but before approving a replacement ($250+) I switched the right speaker with the left speaker(which was not buzzing) and the buzz continues to come from the speaker in the right rear passenger door. I suspect now that there is nothing wrong with the speaker itself and that there might be something wrong with the signal feeding that right rear door which would suggest a problem with the radio/amp, etc. Anyone have experience with problems such as this one?

Since it increases with engine RPMs, I would check the alternator. I have had old cars do this when the alternator is either going bad (bad diode) or the brushes are getting short and need to be replaced.

Otherwise start looking for loose ground wires, etc... It sounds as though you have a ground loop occuring through that speaker. The speaker itself is good (witnessed by you changing the speakers).

if you can get a hold of a tech2 you can test tone each channel with the engine off and then on that may help narrow down the problem. you may be able to kind of do the same thing with the radio just adjust the balance fade to that one speaker and see if the buzz is there with the engine off and just the key on.

my 2003 it was a faulty radio amp under center console seems to be a common problem. if you try smacking the center console it may stop the buzzing momentarily but that is most likely your issue

pull your center console lid storage compartment out and wiggle the connections at the back of the amp, as well as the back of the rear seat radio/HVAC controls. Unplugging them and spraying some electric contact cleaner in the connectors won't hurt. You can also pull up and remove the front cup holders and check the main harness connector there also, or the one behind the traction control button. I doubt it is the radio, and if any thing may be the amp. If needed I have two good one for sale if need be since I switched my amp out to the LUX y91 style amp.

Sounds like you figured out its not the speaker.

If you wanted to verify it 100%, you can buy a few feet of wire if you don't have it, and remove the bad wiring from the harness/head unit and run new wire there with only a couple feet and connect the speaker. That should confirm if its your factory wire that would have got a cut or fray in it somewhere, (probably at the door), or if its the channel and you have a problem with your amp.

Once you confirmed all four speakers are good, You can either try to find the damage and repair the speaker wire, (by cutting and wrapping or soldering it (but that's not your best option, just a cheap easy one), or (what I would do) is to just replace it. You can get a section or two 20-25 foot rolls of whatever size that little wire is for $5-$10. Then tie/wrap, or solder, the new piece to the end of the old (tape the connection to smooth it out). Use some dialectic grease to lube the wire, and pull it through (leaving the end for where your speaker goes or a little extra for error). Pull through all the way for each little section you can for the least resistance on the wire. Once you get it up to the head unit, cut it off after where you connected on the new wire, and replace it into the harness/head unit.

If its a bad amp, You could probably find a used working one for cheap. I wouldn't be surprised if we had members that would send you one for real cheap.

Thank you everyone for your input and help troubleshooting. So far simply turning the rear amp/center console unit off and on has eliminated the buzz. I am rarely back there and didn't think of doing this but so far, so good. If it comes back then I will open up the console and reset all the connections. Thanks again!

glad you got it sorted out. You found your problem. If it comes back again carefully pop out that unit with a plastic trim removal tool and clean the connections (large 24 pin connector) with electrical contact cleaner. It has been a known issue for some.