Introduction:

The reasoning behind this project was two-fold:

1) Hope for a fix for my intermittent XM reception issues when traveling West and South along with reception with the sunroof open, and

2) Updating the look of the antenna

What's needed:

You'll want to acquire an antenna from a 2012/2013 Chevrolet Malibu. I chose this antenna because it is honestly the best looking antenna that GM makes. Far superior to those planted on top of the roofs of Cadillacs.

The part number for the bare (black plastic, not painted) antenna is 20837394. The part can be had for ~$40 from Amazon. If your car is painted black, then 22790992 is what you'd want as it comes painted black from the factory. It is only a few bucks more. Unfortunately, I am unaware of any other part numbers for painted antennas.

I can only confirm that this fits 2006-2008 Grand Prixs. 2004-2005 would physically fit but OnStar will not work with this antenna as your OnStar antenna is on the front part of the roof near the rear view mirror.

Pictures and Process:

Here is a comparison of the existing antenna and the new one:





The antenna cover is attached to the antenna base with 6 small torx bolts.

Some test fitting of the antenna cover on the vehicle:





The base of the antenna changed a bit. It is now ~19 mm square versus a ~19 mm circle:





This isn't much of an issue as there's a guide out there about swapping CTS antennas. You will "simply" have to modify your OEM circle in your roof to a square.

Another thing that change was the FAKRA connectors. GM went from three down to two. They basically combined GPS and cellular into one. This isn't a problem as a Y adapter can be made. Custom made from China (eBay seller) for $9 shipped:



The inside of the new antenna:





The underside of the antenna cover:



The OEM drilled hole in the roof:



You want to start off by tapping the area up with some painter's tape. Make sure you line up the tape to something straight. If not, your antenna will be crooked. Once you finish with that, take your measurements and make a ~19 mm exposed hole with the tape. From there you'll want to get a file and make the hole into a square:











Make sure you take your time. I didn't at first and made some mistakes (scratched my paint). I'll be getting the entire roof painted anyway due to some rock chips up front:



Once you finish up with the hole, then do some test fitting of the antenna base:







The next thing you want to do is apply some touch up paint to the filed area and block off the smaller hole with some silicone or epoxy. I used some silicone from Advance Auto:





Here are some pictures of the base of the antenna protruding into the vehicle. I placed a plastic bag in the headliner area and taped it to the roof so that it would catch any and all shavings along with any paint that dripped:











I got the antenna cover painted the color of my vehicle for $35. Here is the finished result:











Impressions:

My XM reception has indeed improved. Travelling West and South don't seem to cutoff anymore. Likewise, listening to XM with the sunroof open cuts out a lot less than before depending on the direction traveled.

The difficulty involved in this project wasn't too bad. The antenna definitely updates the look of the car and was worth the investment.

Good luck if you plan on tackling this and feel free to ask any questions in this thread!

 

Very nice write up!! I have an aftermarket antenna and I wanted to put it where the factory one was, but I couldn't figure out how to drop the headliner to get to the underside of that antenna. How did you do it? Also do you think if I "gut" the inside of the factory antenna out to put my aftermarket one (http://www.techronics.com/caraudio_1...IUS-SC-C1.html) the square job, would it pick up reception fine? Thanks!!

 

You have an Impala so I'm not so sure how to get your headliner down. You would probably have to head over to that other site and access the service manual.

Do you have the factory XM? I'm going to assume that you don't since you plan on installing that aftermarket unit. Either way, you're going to have to wire down that antenna from the roof to wherever your aftermarket module will be resting.

I suggest that you look into maybe acquiring the OnStar/XM antenna combo (looks like your current one) and then getting a FAKRA connector harness to adapt to what your aftermarket module requires.

 

"Another thing that change was the FAKRA connectors. GM went from three down to two. They basically combined GPS and cellular into one. This isn't a problem as a Y adapter can be made. Custom made from China (eBay seller) for $9 shipped:"

Guess I'm a......little......slow...on the uptake here. Can you use this antenna for the"factory" GPS?? since I added one to my 07. Looks damn good keep up the good work and posting.

 

Nice shark fin !!