My dummy Onstar antenna was in sad condition on my 2005 9-5, the rubber was cracked and split. The latest wind storm here finally finished it off by literally blowing the rest of the split rubber cover off!

Since I've had a new GM truck Onstar antenna laying around for a while (the exact same style as on the 2006+ 9-5) I decided it was time to make a go of mounting it and maybe even integrate it with my aftermarket Sirius.

First of all through testing, I determined that the onstar/gps/xm antenna I had WILL NOT receive Sirius signals, so that was out.

Secondly there were slight differences in the mounting that required me to break off 1 alignment tab on the GM antenna and remove a plastic clip, no big deal. Probably using a 9-5 specific antenna for 2006+ would eliminate this, but I was going for cheap, and the antenna I used only cost me $30.

Modification: Sorry, no pictures of the process.

1. Remove the 6 t10 screws holding the upper plastic cover to the base, and pull up on the cover. It will come right off.

2. Remove the t10 screws holding the antennas to the base, cut off the connectors for the wires and pull out the guts, toss it away.

3. Take a Sirius antenna ( I used the older "dot" style) and pry the covers off of it to expose the antenna. The plastic covers are usually held on with sticky tape and not much else. toss away the covers and magnet base. I had to use dykes to trim down the inner antenna base to no larger that the actual antenna inside. It should now be just small enough to fit inside the rear of the Onstar antenna cover.

4. Either drill the opening of the Onstar antenna base large enough to pass the Sirius connector through or cut the Sirius antenna wire. Mine had previously been accidentally cut and repaired, so I just opened the wires back up to pass it through the Onstar base.

5. Reassemble the Onstar antenna base and cover, plug it all in temporarily, set the antenna on the roof and make sure it works! You may need to play with the positioning of the Sirius antenna inside the cover to get it to fit right and get good reception. Mine was a good as the original Sirius antenna when I tested it. Once you are happy with it, hot glue the Sirius antenna inside the Onstar antenna cover and reassemble it.

6. Mount up the Onstar antenna ( I added a little RTV around the inner section of the base to be 100% sure it would not leak) and route your wires.