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If one of the radios the eeprom was read on I'd suspect some kind of data corruption causing it, the output to that channel is programmable in the amp IC and it's possible the routine is looping for some reason, most of the code to run the radio resides in the flash eeprom but basic setup data is also stored in the eeprom everybody has been messing with, if you have a backup copy of the original eeprom burn it back and see what you have

The first 2 times it happened was actually before I swapped the radio to MyLink. That was one of the main reasons I decided to finally get the swap done. I thought it might have something to do with the radio. It has happened once afterwards. MyLink is working great BTW.

Maybe a ring notification like @ChevyGuy says. If it happens again, I will try turning off my phone and see what happens.

After the last time it happened, I plugged in the OBD reader. There were no codes, but I told it to reset them anyway. Maybe that did something. Only time will tell. It doesn't happen very often. Only 3 times in a few weeks.

 

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It happened again this morning. I turned off my cell phone with no effect. I turned everything on and off, clicked all the buttons and knobs, made an onstar call, all with no effect. Finally, I put the car in neutral, shut off the engine and then restarted it. The noise continued after the restart, but then the Service Stabilitrac Warning came up on the DIC and the sound went away and then the warning went away.

Maybe it has something to do with the negative ground cable problem. Either that or one of the modules has a problem. Or maybe there is a time bomb in my BCM that was designed to go off 1 month after the B2B warranty expired.

 

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Another radio to try ? there have been radio issues reported with the ground problem but never one report of a noise like that, at this point process of elimination since no codes are set, the Service Stabilitrac Warning is a clue of some buss trouble---hmmmm remember reading about the differences in the comm speed and bit size as GM changed the architecture spec, white automotive is the expert and he re-writes the code to accommodate these changes when upgrading to a newer radio, so if its a newer radio this can be the cause of erratic behavior on the buss, something is initiating the sound which is developed in the radio for sure

The noise started when the stock green screen radio was still in the car, and continued after the upgrade. I do have two more radios I can try though.

 

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Agreed.

Note that many code readers are limited and may not read all the codes in the car. You might try a different one, or see if there's a way to get expanded capability.

Good point. Maybe I can find someone with a Tech 2 that would be willing to scan the codes for cheap.

 

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Do you have OnStar service? I'm not sure how that works, but doesn't it have a phone number attached? I wonder what happens if someone calls your number?

I never renewed it after the initial trial period. I think there is still a number, but I don't think it works unless you pay for minutes. I will try calling it to see what happens.

On a side note: It was raining today so I decided to test the Stabilitrak, Traction Control and ABS. They are all working perfectly, LOL.

 

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Something else you can try is call GM's Infotainment group. Maybe they can identify the sound.

Good idea.

I tried calling the car and it says, the Verizon number you are calling is not available.

 

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Door chime sound works OK?

Yes, everything in the car works perfectly. No warning lights or notifications.

I noticed that my battery terminals are highly oxidized. I am going to clean them and all of the ground connections today. I also noticed that my headlights are starting to dim when I press the brake pedal. Maybe my battery is not very strong anymore, and the terminals are not getting a very good connection causing the BCM to do strange things.

 

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Update: I cleaned the oxidation off the battery terminals and a couple ground connections and I haven't had this come back yet. I will update this again if it ever comes back, but I am thinking it had something to do with the grounds similar to the negative cable problem others have had. I also probably need to start thinking about a new battery sometime soon.

 

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I finally figured out what was causing this noise...

This has continued happening at random intervals. Sometimes it would be a couple weeks. Sometimes it would happen twice in a week. The other day it happened while I was in the driveway, so I decided to just start unplugging things until it stopped.

The first thing I unplugged was the add a fuse for my dash cam. It was plugged into the cigarette lighter fuse in the dash fuse panel. The dash cam stays on for about 30 seconds after the car shuts off, and the noise stopped at the same time that the dash cam shut off. I decided to plug it back in, and today the noise happened again while driving. I reached down and pulled out the dash cam add a fuse, and the noise stopped at the same time that the camera shut down.

I have an E-prance Mini 0806 dash cam. It must be generating some kind of electrical noise that is being picked up by the speakers. The noise continues even after I shut off the car and turn off the RAP, so it is probably being picked up by the speaker wiring somehow.

I guess I am in the market for a new dash cam. But, at least now I know what was causing this. LOL.

I liked the Mini 0806 because it is very small, has GPS, and 135* lens, and it records super high def 1296P video at 30 F/S. It also has two micro SD card slots that can each handle up to 128GB chips. But, it is a couple years old, so maybe I can find something better now.

 

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It would have to be pretty powerful to get picked up by the speaker wiring. I think it's more likely that it's being picked up by the FOB/TPMS receiver and activating a "undocumented feature".

Going back and listening to the sound, it's not random noise. I think it's activating something intended for the Asian market.

Question: any chance that the unit is using the car's Bluetooth to warn you about something? Perhaps a recording malfunction (corrupted SD card)?

It is possible that it is being picked up by something else. I was also thinking that maybe it is causing some kind of interference with the OnStar module. There are a few radios in that thing, and I believe it stays powered up for a few minutes. However, the radio turns off when the RAP turns off, so it's hard to see how anything in the OnStar would continue playing through the speakers. OnStar works fine when the sound is playing. I tested that once.

The dash cam doesn't have bluetooth or any wireless technology.

I am looking now to see if there is a firmware update for the camera. I also reformatted the SD card. The camera worked for a very long time without this problem, so maybe it is just getting old. I never remove it from the car, so it gets subjected to some heat.

 

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Keep in mind the radio has power all the time - it just turns itself off when the RAP command passes though the buss. You can hit the radio's power button at anytime and it will come on.

Have you checked to see where the sound is coming from? It might have nothing to do with the car. I know looking at dashcam reviews, at least one reviewer looks for units that will warn you if there's a recording malfunction. It's kind of pointless to have a dashcam that can fail silently so that your unprotected when you think everything is OK.

I updated the dash cam firmware. I also noticed that the dash cam battery is not holding a very strong charge anymore. Maybe it is a low battery alarm. The recorded video looks great, and the camera recorded perfectly until I unplugged it. There were no corrupted files on the SD card, but I formatted it again anyway.

I was positive the sound was coming out of the car's speakers, but now I am not sure.

 

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I recommend a version of this.

View attachment 235714

Mine works great even without a screen. I just copy the micro sd card to the computer once in a while if I need to review something.

This looks very cool. I will look into this one. Thanks.

 

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Plugged it in again this morning after updating the firmware and reformatting the SD card. It happened again almost immediately. I stuck my head up by the dash cam and the sound is definitely coming from the dash cam. It reflects off the windshield and sounds like it is coming from the speakers when I sit in the driver's seat. I was positive it was coming from the speakers, but it is definitely coming from the dash cam. Thanks, @ChevyGuy for the recommendation to check that.

Time for a new dash cam.