I have a 2006 Silverado 1500. It has On Star and XM. Right above the drivers seat, in the roof liner, there is a round thing that looks like a microphone. It is a round piece of plastic that has lots of small holes in it.

Right next to the lights above the rear view mirror, on the driver's side, there is a little black thing that also looks like a microphone.

Can anyone tell me what these two things are?

 

Antennas?

 

I think the thing above the driver's head is the sensor for cabin temperature. I haven't noticed the other thing you mentioned. I'll check it out.

 

I checked the owner's manual and I was right about the cabin sensor but I don't see the other thing you described. Must be different on mine. Good luck.

 

The microphone is up to the right by the mirror or center storage compartment. The thing above your head is in fact the cabin air temperature sensor for the auto climate controls. Mine is a 2006 also.

 

I have a 2009, 1500. Where's the input for the Bluetooth and the On-Star phones ??