Hello,<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

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I have a question about the radio power in my Bose equipped '05 Sierra HD. I just picked up my truck last week and I would like to install XM and my 2 meter ham rig. As you all know the radio power is maintained until the door is opened. I probed the stock radio wiring harness with a multimeter for a 12V wire that remained hot until the door was opened. I came up empty. I found the radio fed with only 12V constant power and some other low voltage signals. <o:p></o:p>

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I did some research and found the grey wire with a black stripe is the dome light sense wire. I found this wire would go to 2.5V+ when the radio should cut off from the dome light. Soooo, being an electrical engineer I would not be out smarted by the truck. I designed a small transistor circuit which sealed in with the accessory power. When the 2.5V signal is sensed it breaks the seal in allowing the artificial power to drop. This circuit controls a 30 amp automotive relay. Any way, I now have an extra 30 amp feed (for amps, XM, CB, or whatever) which follows the radio power and stays on until the door is opened.<?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /><v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"> <v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id=_x0000_i1025 style="WIDTH: 34.5pt; HEIGHT: 26.25pt" alt="" type="#_x0000_t75"><v:imagedata o:href=\"http://www.dieselplace.com/forum/images/smilies/blahblah.gif\" src="file:///C:DOCUME~1OwnerLOCALS~1Tempmsohtml1\01clip_image00 1.gif"></v:imagedata></v:shape><o:p></o:p>

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At any rate, can anyone tell me if there is an easier way. Is there a 12V source somewhere in the truck that is hot while the radio is on.<o:p></o:p>

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Thanks Jeff<o:p></o:p>

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P.S. If this is the only way, I can send the schematic on request. Just drop me a line I'll Mail it to you.<o:p></o:p>

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cny12025@Centurytel.net<o:p></o:p>

go to gmupfitters.com for electrical diagrams.

To tap into power sources, little fuse make a thing called add-a-circuit. You pull out a fuse, put it and another one in the ad-a-circuit and put it back in the fuse holder. Your orignal circuit is left and the extra circuit can now be wired to the pigtail on the second fuse. I bought mine at Autozone, seen them at PepBoys.
Jim

only problem i see is wont your accessories turn off if you manually turn the dome light on?

No, the accessory power stays on until the door is opened. The grey/black wire only becomes positive on the door switch sense, not the dome light. I can manually turn on the dome light, and the XM stays on.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

As far as the add-a-circuit. Which fuse is tied to the maintained power?

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As far as the add-a-circuit. Which fuse is tied to the maintained power?
I don't know with out looking up the prints. That is why I mentioned www.gmupfitters.com. You can get the electrical diagrams and look it up.

Jim