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2004 CTS
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Discussion Starter #1
Hello all,

I own an '04 CTS with a standard stock CTS stereo with no XM. I had a local stereo shop install 2 12" woofers with a 500 watt amp. Also they installed a FM modulator for auxillary input (MP3) 1/8" adapter. These aftermarket upgrades require voltage (obviously) to run. My problem is this- when I turn the car off, the power to the amp and the aux. goes off, and the stereo is all static, which is annoying. I know from all cars I have worked on, there is a way to wire these accessories so they stay on until the door is opened.

So my question is this- does anyone know how to go about wiring this so that the accessories stay on until the computer commands the stereo to turn off (for example, I open the door)? The stereo shop says that it is not possible and it is because the car has "BUS" communications and do not have an accessory voltage circuit. I just don't believe this to be true.

Thoughts?
Josh
 

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06 CTS Sport/Luxury package
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It's true. The bus communications they are talking about, talks with all the different computers on the car. Including the radio, factory amp and onstar.

Though, in my 04 grand prix, it actually had a relay labeled RAP relay. Retain Accessory Power. I haven't looked to see if our cars has it. But if it does, you can tap into that and it will act like the radio.

KOT
 

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Discussion Starter #4
Ok,

I was not able to find the RAP relay, according to alldata, it should be in the right rear of the vehicle in a fuse box. My car does not have that fuse box. As far as I can tell from the wiring diagram, it is used mainly for the moonroof, which my car does not have. So I pulled the radio out and tested power at the radio, no such power is found for retaining accessory power, but I did find that the power outlets (cigarette lighter sockets) do have power after the key is shut off and stay energized for exactly 10 minutes. So I am going to tap my audio accessories power supply into that circuit and they will stay energized for 10 minutes after the key is turned off, which should be fine and shouldn't be enough to drain the battery excessively.

Thanks again for your input,
-Josh
 

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Actually, you mentioned something that I didn't think about. You can use the cigarette lighter exactly how you want to. If you were to pop your hood and take off the cover for the fuse box. You will see the two fuses for the cigarette lighters, one in the front dash (the one you are talking about) and the second one is in the center console in the rear seating area. I believe the front one is 20 amp, while the rear is 30 amp. Either way, both fuses are able to move over one spot. From factory they are set to stay on all the time, you then have a choice to have it turn off with the key. So all you would have to do, is move the fuse over one spot. The center terminal is common to each way.

Also, just to let you know. We all have three fuse boxes. One is under the hood on the passenger side. And the other two are under the rear seat. Just pop the bottom part out and slightly push the rug forward. One is on the passenger side, and the other is on the driver side.

KOT
 

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Discussion Starter #6
KOT,

I now see what you are talking about, thanks for the info, I didn't see in Alldata where the other fuse boxes were, but now I know. I bet if I were to look close enough, I could find the RAP relay now, and tap into that wire. But I will just leave it as is. Good info on the accessory fuses, I looked and see what you mean.

Thanks again,
-Josh
 

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I think the cigarette plugs do stay on all the time. I say this because when I did not know about moving the fuses. I had a gps plugged into the rear outlet, and it never turned off. Even after 5 hours, the little light on the gps was still on and the screen said charging.

KOT
 

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2003 Cadillac CTS
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Wierd! you think they wouldnt do that because of the phone charges. I also wanna find something to hardwire my XM too , first im trying on how to hook it up though haha!
 

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2004 CTS
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Discussion Starter #10
Well the power outlets do not stay on all the time, they stay on for exactly 10 minutes, unless like KOT said, you reposition the fuse in the under hood fuse box. Ideally, we would want other accessories like gps, amps, serius, and stuff like that, to stay on just like our radio does until the door is opened, or the key turned to accessory. I am going to pull the rear seat and see if I can tap into the RAP relay to power my amp, that way I won't have battery issues. I will let you know if I was sucessful.

-Josh
 

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Discussion Starter #11
Success! There is a RAP relay under the rear seat, I just removed the rear seat bottom, pulled the carpet up a bit, there is a 10mm nut on the bottom of the fuse box, removed the fuse box, tuned upside down and removed the lower cover of the fuse box, at the RAP relay (the passenger side-most relay in the box, there is a fat blue wire, I used a yellow quick splice to tap into that wire and ran a wire out from there to my amp (signal) and other aftermarket accessory, and now everything shuts off at the same time the radio will (i.e. opening the door) Thanks alot KOT for your help on this one. STR8LAKIN, I recommend you run the power to your XM and any other aftermarket stuff this way, it was super easy and very efficient.

-Josh
 

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Discussion Starter #13 (Edited)
Lakin,

Sorry, I did not take any pictures, but I attatched a pic of what you need, but dont get the blue ones cause they wont fit around the wire you are splicing into, you need the YELLOW ones, they are bigger. Make sure you splice into the right wire! Best way is to use a volt meter and it will be battery voltage until the door is opened, then it goes to zero volts.

-Josh
 

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Awsome! wow that helps tremendously! Got a question though haha what would i use to run to my XM unit? What kind of wire? would i use the one i used to plug into the wall just cut the wire and splice it? Im new sorry..
 

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Discussion Starter #15
No,

What wire are you asking about? I assume you are asking about the power wire? If so, you can get a car power outlet, like a cell phone charger, but then have to get a power socket to wire to the relay I mentioned, and hide it all under the seat. But the clean way would be to get one of these-
http://www.fantennas.com/myfihrdpwr.html
Go to that link and order one. Or check Best Buy or someting.

-Josh
 

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oh damn that is clean!! haha ! so if not using that? what is the other alternative? Say I wanna power something that the system you should me does not cover? I guess its kind of hard to explain over the forum haha... Thank you sooo much this is helping a million some company wants to charge me 120 to do this! haha
 

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As an aside, if you want true accessory power (not rap) which will turn off when you turn off the ignition, there is one on the HVAC harness. In my car it was the brown wire. But GM has a habit of not being consistent, so double check to be sure.
 

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Discussion Starter #18
There are many alternatives, but I prefer to only do it right, so you wont have issues in the future. $120 is not bad to wire your XM, I own an auto repair shop and I would probably charge $150 or more. I am not sure what else you are trying to wire, but I am sure I could help you figure it out.

-Josh
 

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Im really just trying to wire the XM. I think I could do it myself with really no trouble. The only main concern I have is finding that wire to splice, splicing it haha (cause im a newbee) also a big concern is making a mount in my ashtray, that I am learning slowly. I would like to fab something up like a special mount where it will lay flush.. on my previous post name "sirius" even though its XM haha forgot to put XM for some reason i put sirius lol So if I could do all this on my own with some help along the way I would feel very proud of myself haha. Thank you for all the help shark. Man this stuff is confusing but seems like you can get a grip on it kinda quick with a little help :)
 

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Discussion Starter #20
JIMMYH, Yeah, it is possible to have the amps turn off once the key is turned off, using the HVAC wire or others, but I am really particular about my sound system and I really like the fact that I can shut off the car and the sound system is all working properly until the door is opened. A little anal I guess.

LAKIN, No problem, let me know if I can help any more.

-Josh
 
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