I have been reading around the forums to find an answer to my question, and have found various answers, but that has almost confused me even more. I know there have been many questions like mine, so excuse any redundancy.

I have a double-din head unit that I am getting ready to install into the ol' HHR. I have the antenna adapter, installation kit, and a basic wiring harness (I am aware I will lose chimes, and I don't have onstar). I am perfectly comfortable with the harness wiring, but it is the additional red 12v ignition wire that has me a bit stumped. Some say to tap into fuse #21 on the passenger side of the centre console, others say to tap into the thick pink wire, and others yet say to go into the brown wire in the steering column. What is the best way to go about this? Can any of these methods still give me power, even after I have removed my key, but turn off when I open my door? Also, will I have to sacrifice any sound quality?

 

It would help it you had said which head unit you have? If you have one of the "adapter units" like I had to use, then power to the red wire is already supplied as is the yellow wire. The wire harness has the two plugs such as go into a stock head unit and any extra wires as needed.

 

Ah, sorry. I have the kenwood ddx470. It has a yellow and a red wire coming out of its harness. The yellow is constant accessory power and the red is switched. The harness I got which plugs into the factory harness has the yellow wire attached to it, but the red comes unattached along with a fuse tap. It's this wire that I need to figure out what to tap into with.

 

I attached mine to the fuse panel using an add-a-circuit connector. Forget which fuse, but it says "spare" in the fuse list. Also using the sunroof position for other switched accessories. They have the retained power for 10min after the key is removed.

 

The interface unit I bought to allow use of the steering wheel controls and On-Star had all the necessary colored wires that matched the ones in the head unit harness so it was easy. If you don't have that then I'd agree with the post about hooking it up to the inside fuse box.

 

Perfect, seems easy enough. I went ahead and bought the add-a-circuit, but what size of fuse should I use, and why?

 

Doesn't really matter, i think I used 5amp, just a signal to turn it it on.

 

What do you mean by " Tap " into de fuse box ?

 

Mine is a ATOTO A6 Pro and i have the same problem finding a wire for Red _Accessory/Ignition (+) , if i i use the same as the yellow one my radio is directlyconnect to the battery and never turn off onless i press Off on the unit .

 

If you really want to do it wrong you can use any of the "spare" fuse locations on the BCM for switched power they are on the retained accessory power circuit. #12, #21
The cig lighter is always hot..
You will lose the chimes and the steering wheel controls. The power to the radio is controlled by the computer on a data line that is why the OE radio has no switched wire to it. The correct GMLAN adapter takes the digital signal and converts it, that is the proper/clean/professional way to do it.

Use a fuse tap or connect a wire on the back of the fuse box.