Last september I've changed my factory head unit in my Equinox 07 with the standard sound system for a Sony single din headunit. All was running fine exception of the AM/FM. I checked the continuity on the antenna adapter and ended up suspecting the aftermarket radio.
Sent back the unit where I bought it, the model was backorder so I picked up a Pioneer DEH-6400BT. Plug everything= same problem. I've done some research to find out that the Equinox (and probably a lot of GM) have an amp for the antenna. So I hooked up the remote of the Pioneer to the antenna wire. The reception was better, but not as acurate as my OEM unit.
When I'm a little bit far from the city, I have poor to no FM reception in the truck. Can this be caused by the remote who don't provide enough power for the amplifier? I've changed the radio to gain iPod control and bluetooth but loosing the FM was not in my projects...