I have a 2011 Ford F-150 XLT. Thanks to the forum, I did take the fuses out of the glovebox and installed them. So trailer lights and blinkers work fine. I just purchased a small teardrop tailer. My problem is that the trailer lights are always on when plugged into the truck.They are on even when lights are off and key is out.

I am assuming that the problem is with the wiring of the trailer harness but I wanted to ask here first in case the problem might be with the truck. I have never had a trailer so I am unsure if the 7 prong plug is always hot. Obviously it is on my truck. Is this way it should be?

What do you think may be the problem?

Thanks,

-Sue

 

The 7 pin plugs typically have a + and a -, (12v pos & 12v neg). Sounds like the trailer plug is wired wrong.

 

Usually the BATT + is only hot with the key on. My 01 F150 was that way. I used it to charge the battery on my car trailer for my winch.

 

The Chevy trucks have the charge wire hot all the time.

 

It looks like the truck is the problem. A circuit tester shows that when the key is turned on both the power and the lights circuit is powered. It should only show that the power is on. I also hooked up my trailer to another vehicle and it worked correctly. Some how there is a feedback circuit that when the trailer harness is plugged into the truck and the key is out, the trailer battery lights up the running lights. Now I just need to convince my Ford dealer of the problem so I can get a warranty repair.

Thanks for all of the responses.

 

I don't like that!! Fire hazard, plus you can get feedback from the trailer battery. I guess that's another reason I will never own a GM. Ford and Dodge have the better idea here.

 

My biggest beef with that is that you can discharge the truck battery with a trailer hooked up. Then you are pooched.

It would be nice to have a timer or something like that to turn on the charge wire for a little bit but I suppose I could get off my duff and put a battery in the enclosed trailer to run the lights too. lol!