What is the button on the dash (below the ac) that has a P ^ (triangle)
It's your rear parking sensor "off" switch. If you have a trailer connected, you can turn off the back-up beepers which will go nuts if you're trying to back up a trailer. If you have the lights plugged in, it usually turns the back-up sensors off automatically. Hope that helps!
Search Ford F-150 Questions
Ford F-150 Experts