Welcome to Teamtalk! Are you in NYC?
Could be a few things:
-brake actuator not releasing (you should have a 5-wire plug @ the trailer connector so when you put your vehicle in reverse it releases the brakes)
-your brake calipers could be stuck or sticking. There were some problems with them in 2003 (I had an '03 trailer too, I changed all 4 calipers and pads)
If you can, pull the trailer a few miles then right away jack it up and try to spin each trailer wheel. If there is alot of drag, chances are your calipers are bad.
I was njskier on here.