See attached pic. The pic on the left is looking into your TV connection. Use your meter to read across the connection at the 1 o'clock position (+12VDC) to the 7 o'clock position (ground) with the TV off. If you have voltage, you're going to want to unplug the trailer from the TV.
1988 Coleman Sequoia - popup (1987-2007)
2012 Roo19 - hybid (2012-2015)
2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10