Testing trailer wiring
You asked for it, so here's one way to begin testing your trailer connector for turn signals, running lights, aux power and brakes
A reader asked if I could include articles on how to test wiring for the 7-way connector on the tow vehicle and trailer. So this is my first quick tip on testing the trailer connector on your Tow Vehicle.
Yes, you can use a meter, but…
I’ve used a meter to test trailer connectors for over 50 years. And while meters are the Gold Standard, sometimes you just need a quick test to confirm if the problem is in your truck wiring or the trailer wiring. It’s what I think of as the “divide and conquer” strategy.
Get a 7-way connector tester
These testers are available for less than $15, and will quickly tell you if your truck wiring harness has blown a fuse or broken wire. If all the lights on the tester show that your truck is providing power for turn signals, running lights, aux power and brakes, then the problem must be in your trailer somewhere.
Where to buy one?
This type of tester is available in most Auto Parts stores such as AutoZone, or you can get one on Amazon. Here’s a nice tester from Curt. Order it HERE.
More on this later…
Next time I’ll show you how to use a meter to test the trailer connector, but for now this is the first test.
Let’s test safely out there - Mike
I experience intermittent loss of right turn signal on my 2012 Arctic Fox 25Y trailer. The error message shows up on my 2016 Ford F-350 dashboard. I used to think it was only in the rain, but now it happens sometimes ANYTIME. It comes and goes at will. I have one of those trailer connection testers but it shows the system on the truck is fine. This problem never occurs when not towing. Only when we're towing. When I talked to a service guy at Ford he says bring the trailer in with the truck. We can't do that. When the error code about the right turn signal not working comes up, it does the customary fast blink on the dash, but it may or may not show up on the turn signal in the trailer. Huh? And of course, nobody can fix anything unless it's not working at the time they look at it - which it never happens. We can be sitting still and it will all of a sudden give the code, so vibration doesn't seem to be it. I've sprayed the connection wire and the plug with electric cleaner spray with no effect. I've pulled over in a rain storm and jiggled the plug to no avail. I think it's definitely the trailer. I have another trailer I sometimes pull with NO problems.