I am looking for some assistance with weird problem following installation of am XM radio in my 2004 GX470. I had a Terk XM Commander installed. The vehicle has Mark Levinson sound installed. This vehicle has two antennas. One uses a standard radio connector. The other is a smaller sized radio connector.

The XM Commander uses a FM modulator to connect to the radio. If connects inline to the antenna on the vehicle as shown below. The second antenna connector stays connected to the radio.

XM Commander Control Module
|
GX antenna (standard size connector) <-> XM FM Modulator <-> Mark Levinson Radio
GX antenna (small size connector) <---------------------------------> Mark Levinson Radio

Without the FM modulator installed, AM and FM works fine. When the FM modulator is installed and the XM Commander is powered on the XM radio works great (using 87.9 on the Levinson Radio). When the XM Commander is powered off, you only get static on AM and FM stations fade in and out and there is pronounced static. I contact Terk and they send me a new FM modulator. My installer even swapped out the entire XM Commander with no change.

Does anyone have an understanding on how these two antennas work??
Does anyone have this installled and working on there GX??
Could the antenna on the GX be active instead of passive and therefore expecting something from the radio that the FM modulator blocks??

My installer mentioned that he is experiencing similar problems with 04 Toyota 4runners. My understanding is that the GX and 4runners are distant siblings..

I am running out of options on this. I have been to two installers and they have never seen this issue. Any help on this would be appreciated.

Thanks in advance...

 

I've heard of this problem with VW type amplified antennas that require a special type antenna power plug adapter between the FM modulator and antenna, but the impact was listed as poor AM reception (not FM). Here are the details of a powered antenna adapters www.installdr.com/TechDocs/999014.pdf

These adapters can be purchased local stereo shops or online. The adapter has standard male and female antenna plugs, but also a power wire to be hooked up +12 volt source, such as accessory power or remote radio on wire.

Also check out www.clubxm.com to see if this solution is what others have used to solve the problem.