I do have other posts in here, but shockingly no answers. Figured I go short in this one.

Installed new Pioneer AVIC head unit in 2010 GL450. Since then, radio reception is horrible due to the factory antenna amp not being powered. Since nobody makes a wiring harness for this vehicle, does anyone know which lead powers that antenna amp behind the radio?

Funny, but I have the same EXACT problem in my 2007 SL if anyone know that wire also.... Thanks!

 

Well, I called Mercedes for the second time (dealer) and they were unable to help me. Called Mercedes themselves, and they had me signup for the site which was useless.

So if anyone gets anything from this thread, just know that it is not worth buying an antenna adapter to allow use of the factory antenna as they they do not make a wiring harness for this vehice, and nobody seems to know which wire powers the antenna amp.

I will be bringing it in for to get a universal antenna installed next week.

 

Get a universal hidden mount antenna and just leave behind the radio. They are 10 bux or less on ebay and work great.

 

Do you have one of those installed? I read a few threads where even even the ones mounted to the top of the rear window did not get great reception. Shocked that this hidden one would work. I have since obtained a wiring diagram for my vehicle from Mitchell. It still really does not explain it that well.

If my installer cannot figure it out, I was going to use a universal amplified antenna that mounts to the inside of tailgate window.

 

I have used them on other cars and boats with great results, but not a GL. I would get an amplified one. You can find power at the cigarette lighter outlet.