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Custom Wiring Job on 2008 G6 Sedan aftermarket headunit

6031 Views 8 Replies 2 Participants Last post by  ronnny
Good Day Gents,

I am new to the site and would greatly appreciate any assistance yinz can offer. Firstly, i'm aware that i can buy and adapter for for OEM wire harness for my head unit. I Do not want to do that as that is an absolute last ditch effort. I already cut the harness of the harness, I have wired my chinese 7" touch screen double DIN unit (mostly) correct as when it does power up, it works fine, speakers, bluetooth, radio, you name it. Trouble is i cant locate and acceptable accessory power source for ignition. I Tried wiring the accessory power from the head unit to the brown wire on the ignition switch....that didnt go so well. Sometimes the car wouldnt start and when it did my all my gauges didn't work. So next i tried to wire to the passenger fuse box with a fuse wire adapter. When wiring into ANYTHING i was getting mixed results, all of which didnt suit me. I'd wire into the wind sheild wipers (which are IGN switched) and my wipers wouldnt work. Id then try wirirng to a blank fuse area or my on star (battery powered, i know stupid...) and the car wouldnt start. Basically every IGN fuse id wire to either refuse to power the head unit or start the car or kill that feature......i have a multimeter, ive tested the fuses and the wiring. everything is good on that front. Now, the only thing i can think of, is to run it to the accessory/cig lighter fuse in the trunk......only problem with that is the cig lighter in my car is always hot (battery powered) so in theory, based on what ive already seen, my car wont start....if it kills my cig lighter, i wouldnt care, any thoughts gents?
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I was looking at my g6 book and looking for the same as you. A wire that in run or acc is hot. Looking at the print the white wire off the ignition switch would be the one. Not to confuse with the white wire off a switch right there on the panel you pull loose to get to the radio. This is what I was going to try and do. I got a kenwood head unit and steering remote along with the metra 99-3303. Some days when the car is setting the radio just comes on by itself. May not do it for weeks and then might do it every day. I was going to take the ignition wire for the radio and run to this white wire to see if it would fix this. I would just put the factory radio back in but then you have to go to a dealer to get it programed.
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i never heard that the White wire off the ignition switch was the correct one to splice into. I was lead to believe from multiple sources it s the brown wire....as brown is a (+) IGN wire.....im about at the point to either...A) wire my Accessory power to my always on cig lighter (i would just shut my head unit down by the button all the time) or B) not wire the constant and just wire the accessory and not have my prefab settings saved each time i turn the car off and on. The problem is i think this head unit is drawing to much voltage and its killing functions of the car....if i wired to the accessory/cig lighter, thats a 20amp circuit, should be more than enough power if i dont use my cig lighter..
I was just looking yesterday at my chilton manual wiring diagram. If you are worried about amp draw then just get a 12 volt relay like for aux lighting and run the power through it and your hot in acc/run/start to the coil of the relay.

The drawing I looked at was a charging diagram but showed a black/white to ignition and a white off the acc/run/start both to the bcm (body control module)
also showed a red/white to ignition with pink back to it hot in run/start. The problem is everything on these cars run through the bcm and if the plc sends a signal to check for who knows what it causes things to happen. I do not find a diagram in my manual for the acc/ cig lighter wiring.
I have figured it all out. You will not need to buy a harness Folks, tell crutchfield to kick rocks. To save people a long a dreary process that i had to go through, Lets keep it as simple as possible:

-your going to need to a buy a fuse adapter, wire directly into the passenger floor fuse box (use the windshield wiper IGN fuse; 10A fuse...use the one thats there, if not blown)
-Wire up your basic wires BEFORE YOU DO THE SPEAKERS (the red constant, the black ground, and the Accessory to the fuse box)
-GM wires cars so retarded....You dont have accessory power at the harness, but you have these 3 awesome dark green wires (you need 1 of them for one of your speakers)
- 2 of the dark green wires are GMLAN wires, if you wire ANYTHING to them, it will make your car think your stealing it and try and lock you out/kill the dash.
-Test with your basic wires and hook up the positive and negative of that speaker (dark green wire {right front +} and the light green {right front -}
-If your car fires up clean, and the head unit comes on and that speaker works...(depending if your speakers are blown or not) your in the clear....
-Wire the rest up....i know you can use the brown wire on the ignition switch...but even when i didnt wire my speakers it took to much power from my ignition....best use the fuse box.

I know that seems simple, i assure you it was a pain as i had to replace fuses and test with my multimeter....also GM likes to make it a pain in the A** to even get to the stereo. I plan on doing my speakers this week, but its been quite rainy in pittsburgh as of late. Message back to this forum if you have any questions or concerns....
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also....download the wiring diagram for your G6.....NOTHING is color coded to match..
So you are getting the wire that should be hot, for the radio, when the key is in acc/run off the windshield wiper ign fuse that is on the passenger side of the hump? then the always hot and ground are the factory ones.

Still looking at how to keep my radio from coming on randomly. Was hoping to just move the hot in run wire and keep the rest of the hook up with the wire adaptor I got.

Did you splice in or something to get the steering wheel controls to still work?

not sure i totally understand the question at hand, but. The red with a slight white stripe coming out of your car is your constant...used to retain radio settings when the car is off. The black is of course the ground. As for the IGN power, that needs to be ran to the passenger side fuse box. use a fuse adapter and wire it directly to that. The rest of the wires for the speakers dont match the color scheme of your head unit. you need to see what yours do on the head unit and get the schematic for the car and then line it up....as far as the steering wheel controls for volumn, idk if i even have those...if i do i care little for them so im not sure.....but if you want to retain certain features from your old radio like the DIC, it takes gutting your old radio and mounting it somewhere in yur car and running lines to the new head unit...things i really dont wana do.....im doing my speakers hopefully today if the weather breaks and im going to grab an amp here probaly today.
I guess after rereading our post I was just wondering where you wired into the fuse box on the passenger side of the hump. Did you wire this so that it is always hot or a hot when in run and acc?

My g6 the radio and aftermarket dic all work and the steering wheel controls I even have working. My car came with an amp hidden somewhere in the back of the car. The only problem is the radio coming on randomly when it is parked.
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