[psomers]

To the question of not having 12V on pin 4. My TV is a 2008 GM but maybe Ford does same. My GM had no 12V on pin 4 as delivered. Took a little research but the wire that supplies 12V doesn't come from factory with the wire hooked up. It was taped back close to fuse box. It has a stud with nut outside fuse box where the wire hooks up to get the 12V.
I was told why GM does this but can't remember why. Those that have 12V the dealer must have hooked up
A quick check for brake adjustment. Jack a wheel up and pull break away cable. Wheel should be locked up if RV battery is good. As already stated, don't leave it pulled for very long.