XM Roady XT installation in my 2005 Pontiac Grand Prix

I am also told this has been used successfully to install Sirius Satellite radio in a Grand Prix
and for using an iPod in a Grand Prix

Congratulations! If you have a Pontiac Grand Prix you are very lucky because you can easily install an XM Radio with superior CD quality sound without FM modulators, cassette adapters, extra cassette players, or wires everywhere. You need no special skills, but you will need to invest money in some adapters, a mount and a tool. It is well worth the investment.
You have the receiver, why not do it right?

Click on photos for larger image

Antenna Placement

The antenna is a good place to start the installation. You can run the antenna, and then use it with cigarette lighter power and wireless FM modulation temporarily, while you wait for your adapters and supplies to arrive.

I decided to place the antenna on the roof in the front, behind the On Star antenna. Then I carefully lifted the weather stripping along the top of the roof and tucked the wire in as I ran down the edge. I used a blunt toothpick to do this. I went all the way to the bottom dropped it behind the hinge and then inserted it behind the rubber around the hole in the side. Then I came in to the car in the passenger area. See photos, I outlined the wire path in red.

I bought the replacement antenna because it is slightly smaller than the one that came with my Roady XT, and also so I can use the original antenna when I use a different car. In my previous car, I painted the antenna, I bought touch-up paint at Pep Boys to match my car color. With the Grand Prix, I decided to leave it black since the On Star Antenna is right in front of it.

Direct Connect to the Radio

This is crucial so you get CD quality, none of that FM modulation crap.
Pop out and remove the ring that surrounds the ignition key, set it aside. Next, gently remove the dashboard molding around the controls by carefully prying it off with a plastic knife or a screw driver covered with a cloth. Prop the molding up out of the way.

Remove screws for the bottom tray and move the ray out of the way.

Back of the radio.

Power

If you know what you are doing with power wiring in a car, simply connect the power adapter for the XM radio and the power wire for the PIE adapter.

If you are like me and don't know anything about power and wires, you can cheat and do what I did. The nice thing is I didn't have to use up of my cigarette lighter ports. Also, the wires will be nicely hidden.

Instead of connecting the power from the PIE to the car, I connected it to a 12VDC Extension Cord like this one.
You will need the DC adapter for your specific XM radio, or other device. That way you will be sure it has has the correct voltage.
This is very important. Even if you are connecting directly to the car's electrical system, you need the adapter so it is the correct voltage.
Mine was like this

Both of those power cords will connect to an extra power accessory port like this.
Since you have two male power cords you will need to have an adapter split the power outlet to provide power for both.
I used this 2-Outlet 12VDC Car Power Adapter

Get the add-a-circuit device something like this. I got mine at PEP boys. This allows you to easily connect to the fuse box.

You can twist the wires of the add-a-circuit to the 12V extension cord. I soldered mine together. Then snake the wires of the add a circuit into the fuse box.
Follow the instructions on the package. There are two places that house fuses in the Grand Prix. One is in a compartment to the right of the glove box. Take the cover off of the fuse box. Remove one of the fuses, and plug in the add a circuit. Put the fuse you removed into the add-a-circuit. The add-a-circuit needs to be grounded. I actually drilled a small hole on the metal frame in the fuse box and screwed the ground wire in.
I then tested the power outlet to make sure it worked at this point. You may get fancy and choose a fuse that shuts off with the ignition. That would be a good idea, but I didn't do that. If you did, make sure initiation is on, when you test.

Next plug the two outlet adapter in the power outlet, and then connect the adapters for the XM radio and for the PIE adapter. I realize the equipment will not be mounted where you want right now. Just test to make sure the XM radio works. Turn the car on and push the Band button on your radio. You should hear the XM through your car speakers now.

add-a-circuit in fuse

Dashboard Mounting

Here is where you can put the icing on the cake. Since you have that bottom tray out, you can cut a hole in the back of it (Don't worry, no one will see it). From behind the dash you can insert the antenna wire, the power wire and the audio wire. I put a little tape on the hole so it wouldn't pinch the wires. When you replace the radio, temperature controls, and bottom tray. the wires will be coming out the front of the tray will you can connect the XM radio and mount the radio.

At this point you can mount the radio with a mount that came with it, but I decided to make it extra nice and get a swivel mount to mount the radio in the bottom tray. I ordered the Arkon CM048 Pedestal for only $9.99. There are other similar models. With the tray out of the dashboard I screwed it to the inside right wall of the tray, make sure the screws aren't too big and don't stop the tray from sliding back in.
I mounted on the side instead of the bottom so I could still use that rubber mat on the bottom of the tray. I think this is an ideal place for the XM radio. No need to block an AC vent, and the passenger still has plenty of room.It doesn't block the controls either, but it may appear that way in the photo.

Plug the three wires into the XM Radio, and you are done. Congratulations! top

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I set the background cover of the Roadie XT to match the color of the dash lights.