hf850 in 2005 silverado 2500hd

I am going to install a motorola HF850 handsfree in a 2005 Silverado Duramax 2500HD. It has a Bose stereo with onstar. I want to hook up the mute function, and play the handsfree through at least the LF speakers. Has anyone figured this wiring out, without buying an interface harness for the back of the radio. I know there is a ground activated mute wire on the back of this radio. Which wire is it though.

there is a harness for the 2005 2500 silverado with the bose system on the classic body style. it is called the QCGMCSS-2P

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This, of course, is not the ONLY solution, there is also a Cell-Site GMCSS-2, which QCGMCSS-2P in fact is, with a changed manual and $20 added to the price, and there is our 68631 Interface Lead. Either one of them will mute and use 2 front speakers, so not only it is possible, but you do have a choice.

So, if you use this harness with the hf850, do you hook up the yellow and blue wires from the hf850? Or do you cut the external speaker wire and patch that into the harness? What does the yellow and blue do on this hf850 kit? I know the orange is the mute on the hf850.

Our harness goes right into the HF850 brain, replacing the harness it came with all together and the only wire you need to connect separately is ignition. If I recall correctly, so does the GMCSS-2/QCGMCSS-2, but sq4me will correct me if I'm wrong.

So no one knows how to do this without a harness interface?

If you were installing Parrot, Raytel, Visteon, Bluetouch or Fonexion it would be possible - they have their own mute relays. Motorola does not, so to mute it you need 1 of two: 1. Radio with a Mute input or 2. Harness which will either use Telephone Input function of the radio or provide its own Mute relay. Of course you can build a mute relay yourself, but the time spent will hardly justify it. Add to that the OnStar and the Mute relay becomes a necessity either way, even in addition to the Telephone Input radio mute.

ok, so all gm silverado gen trucks have a mute function on the radio. I did one of these kits in a 2005 silverado non-bose and just muted the radio via the pin for mute from the hf850. So no one has done that?

 I'm late to the party on this one.  The problem you're going to run into with the hf850 is that there is no low level output.  By hooking the speaker output to the to the gmcss-2 the sound is going to blow you out of the truck.  This is so late you have probably already expericed this.  Is it to late to get an ihf1000?