GMOS-04 on Chevy Tahoe 04 sound problem

Mstong

New Member
So my brother has replaced my interface, as it was not working anymore. (Installed a new gmos-04)

the sound is now working again, BUT our problem is now that the sound is working, about every 15 seconds the sound cuts off during the music for about 2-3 seconds then continues.

does anyone know why?
My brother is saying he needs to bypass the bose amp that’s in the car.
It has the original Bose sound system
 
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Maverick6587

Silver Supporter
Do you have an aftermarket amp installed to make up for removing the bose amp?
More than likely the bose amp is failing.

There are two of us that are currently working on replacing the bose amp to see if it fixes a similar problem as yours. Random cut outs or not turning the music on until the door chime sounds.
 
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Mstong

New Member
My mistake it’s not a factory amp it is the Bose amp that was originally in there. He said the amp is failing and he need to bypass it and reconfigure the speaker wires directly to the harness?
 

Maverick6587

Silver Supporter
I'm confused... The Bose amp... You're saying it is NOT a stock amp? It's an aftermarket Bose amp?
Did the vehicle come with a Bose amp as well though?
 
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Mstong

New Member
Lol I’m sorry.

it is the Bose amp that came with the vehicle. My brother said I may need to replace the amp but if I do I need to find an exact match. Not sure what he means by that.
I’m trying to avoid taking it in to get it figured out. I just miss music 🤣
 

Maverick6587

Silver Supporter
Yeah, I would just go to the junkyard and snag one then. Just pull one from the same year as your Tahoe.

A new Bose "stock" amp will cost a few hundred dollars.

Here's a link on how to remove the old one/find it in the junkyard, in case you haven't removed it before.

 

Reprise

Lifetime VIP Supporter
(FYI... he means that if you replace the OEM Bose, it has to be with the exact same one (year / vehicle.) The harness leads changed on the amps a few years after they started putting in the Bose components; then they went to a revised amp chassis, as well)


Double-check the connections, per your HU and the GMOS instructions, both for wire-wire function, as well as connectivity. If you weren't getting that cutting out before the GMOS, it's kinda 'beyond coincidence' that the amp would 'fail further' at the same time. Yes, the Bose amps do go bad, with age; I'm not defending them. You may have a short in one of the Bose amp leads, as well (power / ground / turn-on lead). Although you'd probably be blowing the amp fuse (in the fuse block) if this were true, especially if it's at the power or ground wires.

Further isolating things, you could attach a speaker to one of the HU outputs (assuming it has an internal amp of its own), verify that it's working OK, repeat for the other channels, then bring back the GMOS and test that. Don't forget to adjust your balance / fader controls when doing this; it's not good to drive disconnected outputs, especially at higher levels.

Also, speaking of fader / balance, the OEM head unit is supposed to have fader / balance centered, before you remove it and install the new HU and GMOS. Axxess does specify this (and I'll admit, I've forgotten about it myself.) Haven't noticed anything adverse when I didn't do this, but if they specifically advise to do this, it's worth following the instructions. (the potential problem is permanently out-of-sync levels, if it manifests itself)

Finally, if you do decide to replace the amp with an aftermarket (admittedly, the best long-term strategy, if you want more power than the amp in the HU can supply), you can swap out the GMOS-04 for a GMOS-01, which will still preserve chimes (comes with the outboard chime box), but not the amp leads (you'll be running new ones, anyway). Using a harness of some type will save you from having to cut the factory harness and potentially misidentifying the wiring / creating a mess to figure out. If you like / use OnStar, then I think you may need the GMOS-02. Verify this at Axxess' site (which is difficult to navigate / narrow down choices, for our older vehicles).

Don't forget that if you have steering wheel controls, and want to keep them, you'll also need the ASWC from Access, as well (it integrates with the GMOS, via a subharness)
 

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