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GMOS 100, Alpine HD138BT and external amplifier install

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For reference...






I am trying to install the head unit and an external amplifier in a truck I recently purchased, so I have really no clue how the GMOS adapter, OnStar, the door/warning chimes, or GM harness work.


There will be the Alpine head unit, a 3-channel amplifier, new front speakers and two subs in the final arrangement. The rear speakers will be left alone.


Can I have OnStar and chimes go directly from the Axxess unit to the rear speakers? Does the Axxess unit provide a powered signal to the speakers?


Furthermore, if I wanted to use all four main stage speakers, how would the OnStar/chimes work with the powered signal from the amp? Would there be two sources of power/signal going to the front speakers? Or am I thinking about this the wrong way?

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I was told that the amp will increase the sound of the chimes, OnStar and turn signals so you may want to run a separate speaker under the dash just for those sounds. That's what I did on mine when adding Boston Acoustics components in the front and speakers in the rear door along with a 10" sub and Kicker amp.

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I'm not going to use the amp on the rear speakers. I'm hoping I can send front speaker output from the Axxess box to the rear speakers. But I am not sure if it works that way.


If I got it in my head right, the front white/gray speaker wires from the Alpine head unit would run via a harness to the Axxess box. That signal would get altered/mixed with OnStar/chime signal and sent via more white/gray wires on another harness to the GM harness and played over the front speakers. ALPINE <harness "A"> AXXESS <harness "B"> GM harness


But I am not going to send any signal to the Axxess box from the Alpine head unit. The only signal I need from the Axxess box is the OnStar/chime stuff.


I'd like to cut the front speaker wires in harness "B" from the Axxess box to the GM harness, and route that output from the Axxess box to the rear speaker wires coming from the GM harness.




And there is a way to control the volume on the Axxess box.

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