GM Bose System High-Frequency Noise!

I recently purchased a new 2005 GMC Envoy XUV with the Bose Premium Sound AM/FM/CD/Cassette option. (It also has the rear-passenger radio & climate controls.)

The problem I am experiencing is a very high-frequency noise emanating from the rear speakers - but ONLY when the engine is running. The noise does NOT vary by engine speed. But it is constant regardless of the source and regardless of the volume level. It is difficult for some people to hear but becomes obvious once the engine is shut off (and thus becomes noise-free).

My dealer has replaced every radio component in the car (head unit, wires, connectors, amps, speakers), installed filters and noise suppressors, re-routed the wires - just about everything you can think! But nothing has worked. For now I am forced to either "deal with it," leave it off, or turn off the rear speakers by activating the back-seat headphones. I'm not too happy, as you can imagine.

At this point, I would explore employing some kind of band-pass or band-stop filter, either at line-level or speaker-level. Just anything to kill the noise!

Any help would be GREATLY appreciated! Thank you.

Brent

I'd stay on the dealer and make them either find a fix or get you a different vehicle... but have you checked the engine ground strap or the negative battery terminal?  In some new builds, the graound connection gets painted and that can cause noise in the audio system.

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Certified Security Specialist
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Thanks for the quick reply guys. I am in the middle of a formal dispute with GM and the BBB Auto Online but the problem is that a lot of the GM technicians claim they simply don't hear the noise. So they are reluctant to replace my car unless they can confirm this with more than one dealer. (A few of the service writers at my dealership confirm it but others, including the service manager don't. A second dealer claims nobody hears it.) I'll admit it is extremely high-pitched and difficult for most people to hear but I hear it and it drives me nuts!

They are sending an independent technician to investigate the problem very soon but they have made it clear that I can not interfere or influence this technician lest I have my case thrown out. I need to show them how to hear it because to the casual listener it is not obvious. And it's very directional. Just moving your head a few inches out of the sound path makes it inaudible. But I don't want to jeopardize my case.

So I am thinking in the worst case scenario, if they deny me any restitution, what I can do to eliminate or at least mask the noise by employing a filter of some kind. Anyone know how I might go about such a task?

Thank you again!

Brent

Get access to a RTA, take it with you to the dealer, turn it on and hold the mic where you hear the noise, turn the radio on, watch the spike on the meter, tell them to fix it now or I am going to sue the living shhh out of you.

The problem with high pitched noises are that some people can hear them and some people can't. It varies person to person. The RTA doesn't lie, and it can be used as proof. By the way, RTA=Real Time Analyzer

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Certified Security Specialist
Always check info with a digital multimeter.
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Auex,

Excellent idea! Hadn't thought about that. Any thoughts on where I might obtain one? Perhaps a pro-audio or electronics repair shop? I know a great pro-audio tech (guitar amps, musical instruments). Perhaps he has equipment. I doubt Radio Shack sells anything like that.

Thank you again!

Brent

If you can rent one, or borrow one go nuts, but don't buy one just to prove theres a problem.  That is a very good idea by the way.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

Alot of higher end stereo shops have them. Maybe meet the gm tech at one and use it. But it really depends on where you are. They are EXPENSIVE though.

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Certified Security Specialist
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Tell Darwin I sent you.

I've been sick lately, sorry I won't be on much.

By the way I am with you on this one. I am one of those people that can hear higher pitch noises and they drive me crazy.

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Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.

I've been sick lately, sorry I won't be on much.

Glad to hear you can hear these things, too! Wish I couldn't!

Brent

Guys,

I was able to "assemble" an oscilloscope consisting of a studio quality condensor microphone, analog-to-digital converter, and laptop computer with some trial software that displays graphs of the entire audio spectrum (20-20,000 Hz) in numerous ways that can be captured and saved. I'm just finsihing tests and will try it in the car tonight when all is very quiet. Man, I hope this works! I'll post my results.

Again, thank all of you for your time and excellent suggestions.

Brent

Wasn't able to isolate only the high-pitch noise with the oscilloscope but was able to record the noise successfully to digital tape which I transferred to my computer and increased the gain. It is absolutely audible now. There is no way anyone can listen to the recording and claim they don't hear it now.

Also, had an independent audio technician (sent by the BBB) come out and listen to the radio. He confirmed the noise and will be reporting his findings back to the BBB. Just hoping we'll get somewhere now - FINALLY. (This has been going on since early January 2005).

Brent

Good stuff. Hopefully it works out for you.

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Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.

I've been sick lately, sorry I won't be on much.

Thanks auex. I appreciate your help and concern.

Brent

The problem sounds like it is in the routing of the wires or in their connection to the various components. The noise may be generated by a bad connection from the connector plug pins to the mating pins in either the radio, rear seat audio control unit or the amp. Has the dealer installed and rerouted in a different path the shielded audio lines between the radio and rear audio controls and then to the amp? There are also a couple of GM service bulletins they can refer to that cover noise only on the rear speakers. One details what I just mentioned and another lists a possible problem with the transfer case module ground. The other thing to note is any characteristics of the noise. You mentioned that it didn't increase with RPM. Does the noise go away if you turn the radio off with the engine on? Is it affected in any way by using other accessories in the vehicle? Are you sure it is noise coming from the speaker and not from the powertrain or drive belts? Troubleshooting noise is not always easy. Be patient and GM will fix it once they etablish what the noise is and how to duplicate it.

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sparky

Sparkle,

The dealer has replaced every component of the radio system and has rerouted the wires, replaced connectors, and installed noise filters for the power and antenna.

I'll have them check for the service bulletins you mentioned as I hadn't heard about those previously.

The noise is always present when the engine is running AND the radio is on. The only other time the noise is heard, with the radio off, is when a warning tone (fasten seatbelts, low fuel, etc.) comes on as it activates the radio system to sound through. When the tone ends, the noise disappears (provided the radio is still off). It is absolutely a radio/speaker noise.

Thanks for your thoughts.

Brent