Auto body repair & detailing: Door Wont Stay Open, gmc yukon, barn doors

Question
I have a 99' GMC yukon, 4dr and 4x4. One of the back "barn" doors will not stay open, it constantly closes itself back. Is there a new hinge I need to buy or another part.  Also, after hooking up to my trailer my headlights have decided not to work on the dim setting. The brights work fine. I have consistently had troubles with the electrical system when running a trailer.  Any help is greatly appreciated! Thanks

Answer
BO

THE BACK DOOR THAT DOES NOT STAY OPEN QUESTION IS THE ONE THAT I MAY BE ABLE TO ASSIST YOU WITH.
THERE SHOULD BE A DOOR CHECK ON THE BACK DOOR LOCATED ON THE DOOR SHELL AND BODY.

LOOKS LIKE A STRAP THAT GOES INTO THE BODY.....THIS IS EITHER LOOSE OR BROKEN AND WILL LET THE DOOR
SWING AROUND. THEY ARE NOT THAT EXPENSIVE BUT TO BE SURE I WOULD RUN BY A BODY SHOP AND LET THEM PEEK AT IT AND OFFER AN OPINION.