Xm Antenna Routing-2008 Gmc 3500 Hd

[fastcw]

My 2008 GMC XM antenna is blocked when I have my camper on the truck.

 

I need to connect an external antenna into the existing antenna cable.

 

I have the radio out, and was sorry to find only one antenna input, instead of a separete input for XM, which means there is a junction box or splitter located somewhere that connects the outside AM/FM whip and the XM antenna together.

 

I have traced the antenna cable to the area behind the glove box. Before I tear out any more panels, does anyone know the location of the junction or splitter?

 

Or any other suggestions?

 

Thanks,

Dennis

 

Another question: I'm looking at external XM antennas, and they seem to all need 4.7 VDC, which they say is supplied by the XM receiver.

 

I have checked for voltage on my radio ant connector, and don't see any DC voltage.

 

Is it possible for me to add an external antenna to this system? Does the antenna mounted on the cab use 4.7 volts?

 

I tried to pop the cab antenna up, but it looks like it is secured from the underside. Does anyone know how to get it loose?