Hi all, New owner of a 2003 Yukon XL 2500 4WD SLT. I have a few questions: 1. There's a sound like a small electric motor when I turn the key on, that seems like it's coming from mid to rear of the truck. It just turned up this morning, I haven't heard it in the last week. It comes on with the key, engine running or not. It lasts until I turn the key off, when it winds down and stops. The climate control is turned off front and rear. 2. I don't seem to be getting 12v power from the 7-pin trailer connector's charge line. Is there something I need to install to enable this? 3. The previous owner installed an AUX input in the dash using some sort of adapter device interfaced to the head unit, but I haven't been able to figure out how to use it. The head unit is the stock 6CD changer with XM radio. Any ideas on what might have been installed before I open up the dash to look at the device? 4. Is there a way to have the fogs come on with the headlights?