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Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 29457
Experience:  GM Grand Master Technician 2007. 14 year experience.
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I have an 06 GMC Envoy XL Denali that I am the second owner

Customer Question

Scott - I have an 06 GMC Envoy XL Denali that I am the second owner of. We bought it CPO in 2008 after it was a GM executive lease. It has been great with only one exception: a Bose left front channel issue. This started to occur about a year after we had the car and is unpredictable, not due to any condition or weather. We had it o the dealer many times over the years and they have been unable to fix it. The replaced the stereo/navy head unit, the front dash and door speakers, looked in the rear door for wire breaks, all to no avail. It can be present when the car is started, going over a bump, closing a door (especially the left rear), putting down the second row seat and sometimes even hitting the brakes. When occurring, it is constant. If I have the stereo one one notch, you can hear it the same as if I had the stereo up further. It is present in chimes and the turn signals. If I was occurring and I hit the brake pedal, it has a sound like I just ac'd it. Do you have any
Submitted: 1 year ago.
Category: GMC
Expert:  Eric replied 1 year ago.

hi,

You dont mention what it is doing - popping or thumping noise, static, or something else?

Customer: replied 1 year ago.
Sorry. It can pop but it is usually a constant humming. If you need me to, I might be able to get a video of it.
Customer: replied 1 year ago.
It sounds like a bad ground if someone had hooked up and aftermarket amplifier on cars I owned when I was young and didn't ground correctly.
Expert:  Eric replied 1 year ago.

HI,

Ok, if you are able to record it and post it to you tube and post a link to it here, it would help.

There is a service bulletin out on noise from the left front speaker, but it is strictly for a popping or thumping sound

Customer: replied 1 year ago.
I have tried multiple times today but couldn't get it to occur. It isfunny like that. I think I drove it five times last week and it only happened once. In other cases, I could have had it happen all five times.
Expert:  Eric replied 1 year ago.

HI,

Ok, to be honest, without hearing it, it may be impossible to know the cause. So if you like, we can leave this open until it occurs again and you can record it

Customer: replied 1 year ago.
Sounds good to me. I can almost guarantee it will happen during the week so we can take it from there. Thanks!!
Expert:  Eric replied 1 year ago.

HI,

Sounds good. First, bookmark this page. Then to leave it open, just dont respond to this post now. That leaves it open indefinitely until you post back.

Customer: replied 1 year ago.
Eric - My wife kept forgetting to record it for me but she finally got it today. I don't really want to create a profile on YouTube... Do you have any other options that you use like Dropbox?
Expert:  Eric replied 1 year ago.

Hi,

You can use MediaFire, Dropbox, or other source like that and post the link here for me

Customer: replied 1 year ago.
Eric - I was able to upload 2 of them. Can you tell me if you get them both?https://www.dropbox.com/sh/xzxknry8rp400m4/AAAvUjVQuxOkk3C-K3m0fj_Ya?dl=0They show how it stays constant unless the volume is all the way down. How it reacts to certain things like a door opening. The only thing she did not get was the popping feedback if you pressed the brake while the sound was occurring. I hope this helps!
Expert:  Eric replied 1 year ago.

HI,

Got them both. I cannot say that I have ever heard that type of sound from one of these before. I have a buddy coming over tomorrow that is a retired GM engineer that I am going to let listen and see if he knows what is causing this sound

Customer: replied 1 year ago.
That'd be awesome, Eric. It has been tough because we have been dealing with it for many years and GM wa never able to fix it under warranty so it continues to be our problem. It's been a great vehicle otherwise!
Expert:  Eric replied 1 year ago.

HI,

Will try my best on this and will talk with you tomorrow after my buddy listens to it

Customer: replied 1 year ago.
Eric - here is another copy with her driving around with it. You will notice that it isn't just the constant noise, but one that seems to fluctuate with the RPMs as well - almost like a badly grounded aftermarket stereo or amp, though mine is bone stock.Here is the link:
https://www.dropbox.com/s/n1pb7n229xzfgoj/Video%20Dec%2017%2C%204%2003%2017%20PM.mov?dl=0
Expert:  Eric replied 1 year ago.

HI,

Ok, my buddy and I have listened and listened and are honestly stumped on this one. If you like, I can opt out and see if another expert may have an idea

Customer: replied 1 year ago.
Eric -
If you think that is best, ***** ***** ok with it. Either way, I can also provide the VIN if someone had access to the GM dealer vehicle history report.
Expert:  Gm Tech (Cam) replied 1 year ago.

Hi there, I am Cam. Can you post your bin for me?

Expert:  Gm Tech (Cam) replied 1 year ago.

Vin not bin.

Customer: replied 1 year ago.
I have attached it in Dropbox with the other fileshttps://www.dropbox.com/s/qrlrv61sehaychu/Photo%20Dec%2018%2C%209%2003%2042%20PM.jpg?dl=0
Expert:  Gm Tech (Cam) replied 1 year ago.

OK, that is a very interesting Whine noise. Can you try something for me. IF you disconnect the small alternator control wire from the alternator, does the noise go away?

I am investigating any bulletins and looking for common grounds and such that may be related to this.

Expert:  Gm Tech (Cam) replied 1 year ago.

I found a PI, Preliminary information on this issue. It has some steps to follow.

#PIT3522F: Buzz Noise From Rear Speakers After Bulletin 04-08-44-014B - keywords AMP amplifier door radio sound speaker UQA - (Sep 17, 2008)

Subject:

Buzz Noise From Rear Speakers After Bulletin 04-08-44-014B

Models:

2004-2007 Buick Rainier

2004-2009 Chevrolet TrailBlazer models

2004-2009 GMC Envoy models

2004 Oldsmobile Bravada

2005-2009 Saab 97x

This PI was superseded to update model years. Please discard PIT3522E.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

Rear speaker noise on vehicles with rear seat audio controls (RSA) and Bose amplifier. This noise can be produced from a variety of high load or PWM controlled electrical components (rear window defroster, heated seats...) but usually can be identified as an whine noise related to engine speed (generator electrical feedback). This condition can be verified by turning the RSA on (rear speakers off) and the noise should go away. If the noise is the same the root cause most likely exists elsewhere and additional diagnosis is necessary.

Recommendation/Instructions:

Perform the following procedure to reduce the rear speaker buzz noise AFTER all low level and high level circuit integrity has been verified. For example, it is possible for the system to produce audio output to the speakers even if a (-) circuit has an open. However it will most likely produce undesirable noise in this condition.

Note: Bulletin 04-08-44-014B applies to 2004-2005 vehicles only. The Transfer Case Control Module ground has been relocated on all 2006 and newer vehicles. The information may be helpful on 2006 and newer vehicles.

Important: Prior to moving forward with the directions below, all 2008 model schematics refer to all connectors as the letter "X" followed by the connector number. The letter X is the new global term for connector. Since this PI address 2008 and prior, the connector number will be written both with the letter C and the letter X.

Note: After each step below, re-evaluate the concern. If the concern is repaired, there is no need to continue with additional steps.

  1. Check for damaged harness under the passenger rear 2nd row seat. This step applies to short wheel base vehicles ONLY equipped with AMP RPO UQA.
  2. Remove the passenger side second row seat.
  3. Remove right rear sill plate
  4. Lift carpet and follow body harness as it travels along the passenger rear second row seat toward the amplifier.
  5. Repair any damaged wires and reroute the harness to prevent future concerns.
  6. Remove the AMP connector. On short wheel base vehicles, the AMP is located behind the right rear 1/4 trim panel. Removal of the trim is needed to access the AMP. On extended wheel base vehicles, the AMP is located on the left rear 1/4 trim panel. Remove the access panel in the left rear trim and locate the AMP connector.
  7. Remove the C1 or X1 AMP connector.
  8. Disconnect and pin drag terminals B3 B4 B5 B6 and B12. Use test probe J-35616-6 (BN). Replace any loose or damaged terminals as needed.
  9. Reinstall the AMP connector and evaluate.
  10. Inspect the Bare Wires for terminal Integrity.
  11. Remove the radio and the C1 or X1 connector.
  12. Check terminal tension on C1 or X1 terminal A5. Use test probe J-35616-6 (BN). Replace any loose or damaged terminals as needed.
  13. Remove the AMP connector C1 or X1 and C2 or X2
  14. Check terminal tension on C1 or X1 terminal B12. Use test probe J-35616-6 (BN). Replace any loose or damaged terminals as needed.
  15. Check terminal tension on C2 or X2 terminal E. Use test probe J-35616-6 (BN). Replace any loose or damaged terminals as needed.
  16. Remove the center console assembly from the vehicle. Refer to the Console Replacement procedure in the Instrument Panel and Console sub-section of the service manual.
  17. Locate the C307 or X307 connector to the left of the transmission tunnel. The driver's seat may also need to be removed in order to gain access.
  18. Inspect the connector and see if it is fully seated. Secure connection as needed.
  19. Unplug the connection and pin drag B1 B2 B5 and B6. Use test probe J-35616-4A (PU). Replace any loose or damaged terminals as needed.
  20. Locate the C304 or X304 connector. This is located under the second row rear seat on the driver's side. There is a cut out in the carpet where this connector can be accessed.
  21. Inspect the connector and be sure it is fully seated.
  22. Disconnect the connector and pin drag terminals D3 D6 D7 and C12. Use test probe J-35616-2A (GY). Replace any loose or damaged terminals as needed.
Expert:  Gm Tech (Cam) replied 1 year ago.

Added info may not be needed but may be worth looking into, the bulletin they outline does not apply for a 2006, but check it out anyway.

Important: This procedure will only correct the noise related to transfer case operation. It will not correct the speed sensitive whine type noise, commonly referred to as alternator whine.

Perform the following procedure to reduce the rear speaker buzz noise caused by the active transfer case.

  1. Remove the left side IP closeout panel.
  2. Remove the transfer case control module and mounting bracket from the IP mag beam.
  3. Disconnect the C3 connector from the transfer case control module.
  4. Remove the wire and terminal from cavity A (circuit 2250) from C3 connector. Tape back.
  5. Construct a new ground wire using terminals P/N 12047767 and P/N 12089496. Route this wire through the grommet from the IP out to the engine compartment.
  6. Install the new ring terminal onto ground stud (G105) located on the bulkhead just above the brake booster.
  7. Install the new terminal into cavity A of connector C3.
  8. Connect the C3 connector to the transfer case control module.
  9. Install the transfer case control module and mounting bracket to the IP mag beam.
  10. Install the left side IP closeout panel.