SOLVED! 2008 Trailblazer radio sound cutting out

[sashainwy]

I have a 2008 Trailblazer, and the sound starts cutting out repeatedly, sometimes quickly like a machine gun, and sometimes slow. At the same time, I hear a clicking noise behind my head.

- factory stereo, 99% sure it's non-bose
- vehicle has onstar, but we don't pay for it, and never use it or touch it
- the radio illumination itself doesn't blink or flash, it stays on constantly when the audio is cutting out

I read somewhere that the onstar module is under the rear seat. The clicking does seem to be coming from that general area. Can the onstar module cause the sound to cut out from the radio? I'm sort of considering replacing the head unit with aftermarket that has navigation. Any thoughts, hints, suggestions welcome! Thanks folks!

 

[mrrsm]

While the general investigation that follows involved in this Video concerns issues with the Diagnostics of the Class 2 Network UXXXX Codes...it DOES provide an uncommon view of how to investigate the VCIM Module located adjacent the area near the left rear passenger floor board under a Black Plastic Cover.

By extension, you will then know where to remove its cover and then disconnect the Two Connectors and then spray them out with CRC Electrical Contact Solvent, allow them to thoroughly air dry and then re-attach them to see if this action has any positive affect upon the sketchy speaker sounds.

Even though this information in useful in its entirety... for these specific purposes...advance the video viewing to around 15 minutes along and then observe everything Will Robinson is attending to on that rear floor board and you will become familiar with how to approach the two VCIM Connectors, Disconnect them...Clean Them and then... Re-connect them for this simple investigation:

 

[Mooseman]

You can disconnect the OnStar module completely. This will eliminate it as a possible interference and a useless battery drain. It's located under the rear passenger side seat.

 

[Mike534x]

If you have "UQA" as the RPO code on the list in your glovebox you have the BOSE System. If you do have it, I would inspect the wiring loom that runs under the center console (movement of it will eventually cause chaffing to the harness) that leads to the rear HVAC/radio control head (if its the digital one like the front). While tracking down a battery drain, I noticed my rear speakers were cutting in out, and I would sometimes lose sound completely. Found I didn't have the connector fully seated into that little head unit, and that cleared it up. I figured due to the "switching" function when plugging in rear headphones, in order for the BOSE/Radio to separate the audio channels, then the signal wires from the BOSE amp must be fed through that little headunit, before it meets back at the radio.


SWB = AMP location is hidden behind the rear passenger side cargo panel

Ext/XL = Behind driver side rear cargo panel

 

[sashainwy]

Glovebox codes includes UQA. So I guess I have the Bose?



I do have a little audio/ac interface on the back of the center console.



As mentioned previously, the sound cutouts are instantaneous. Instant off, and instant back on. Sometimes in rapid succession. I get no odb2 codes when I scan for them.

I think I'll disconnect the OnStar first as suggested, since it's right there and very easy to disconnect, and drive it for a bit to see if the audio still cuts/clicks. If the problem is solved, great, if problem persists, I'll get my eyeballs on the center console radio/ac interface wiring/connections, same for the amp, same for the VCIM.

Thanks folks for guidance!

 

[sashainwy]

So far so good. Stereo working normally.

 

[Mooseman]

So it was the OnStar?

 

[sashainwy]

So it was the OnStar?

It does seem that way, unless some wires got bumped, when I rotated the seat bottoms to access the OnStar. I plan on driving it for another month or so as-is. Then I'll plug the OnStar back in, and if the problem comes back, it's confirmed.

 

[Mooseman]

And re-unplug it after. We generally recommend keeping it unplugged for a few reasons: Nobody subscribes to it, It's no longer supported by cell providers and it continuously draws power.

On my 2021, I had free OnStar for 3 months and I never used it. Which reminds me, I have to unplug it

 

[Mike534x]

On my 2021, I had free OnStar for 3 months and I never used it. Which reminds me, I have to unplug it

I'm curious to know how that'll go, I recall reading how it's difficult to remove OnStar on anything 2018+ due to how integrated (the module) is with the BCM and other functions.

 

[Mooseman]

I just pulled the fuse. No adverse effects.

Disable OnStar tracking 2020+

Just posting this here as there wasn't a whole lot of info on how to do this on the newer trucks. I've been wanting to completely disable it on my 2021 GMC Sierra but all I have found was a YT video on how to unplug the antennas, which is not the best method as it's still active, collecting...

gmtnation.com

 

[sashainwy]

I'm calling it good. I put the OnStar module back, but left it unhooked. Stereo sounds good as ever.