Inside Light on Horse Trailer Won't Work in Horse Trailer When Connected to F-350, Works On Others
Question:
Yes, I have replaced the plug. Even before replacing the entire plug the interior lights only of the trailer wont come on. If you plug the trailer into a different truck they do come on. Can someone point me in the right direction?
asked by: Pam
Expert Reply:
The issue here is, with a great deal of certainty, on your truck and it's wiring harness. The first thing you'll want to do before starting is make sure that your vehicle's 7 way connector is free of dirt and debris. It could be something as simple as a dirty connection that is keeping voltage from passing through.
You'll need to determine which circuit on your 2008 Ford F-350's wiring harness is tied into the interior lights; it could be the auxiliary power circuit or the 12v circuit. If it's one of those two, it would just be a matter of making that function active on the vehicle side. If the lights go first to a trailer mounted battery make sure the battery has a charge and that the power wire and grounds are intact. They can also be tied into the running light circuit so you would check it as well.
To test everything out, you'll want to use a circuit tester like # PTW2992 and test the pins on your F-350's wiring harness. You may need someone to help you work through the functions while you test the pins, but if one of the pins isn't supplying power, that is the wire you'll need to focus on.
Once you've isolated the wire causing the problem, you'll want to make sure it is connected to the harness; from there you'll need to follow it back to where it hardwires into the vehicle. Check for cracked and exposed wires that could be causing the short and replace them as needed.
If you still haven't determined the issue by this point, let me know and I can provide you with a few more things to check out. As I initially mentioned, I'm fairly certain this issue is being caused by your truck and the wiring harness on it-not the trailer.
