I have had on and off trouble with the truck trailer connection, getting a "trailer disconnected" message even though lights, brakes etc work. Airstream says Ford brake controllers are too finicky. Ford says they tested their plug and it must be the trailer. Both truck and trailer have been checked for a good ground. (Google says Ford trailer brake controllers ARE finicky.)
Multiple cleanings of the plugs and lashing the plug in place with a pull tie seems to have solved the problem for now but I thought I might add a plug tester to the mix.
I see two levels of 7 pin testers. One is the $8-10 variety, the other jumps to $25-30. It sounds like both test not only the lights etc, but the brake controller. But the description on the more expensive models seem to be more specific about testing the brake controller.
I don't want to spend a fortune on a tester that I will only use once in a while but, I want to be sure that I am testing all of the most important functions especially brakes. Apparently these testers test the truck plug only thus, if the truck is OK, "it must be the trailer."
What are your thoughts about whether these testers are worth a dang and, if they are, is the difference between the two price levels based on better function or playing to the notion that more expensive is better.
DRAGONFLY - 2011, Provan Tiger CX, on a F350, 4WD, regular cab chassis