F250 and Horse trailer wiring
 

I'm posting this for a friend. She has bought a F250 after getting rid of her Chevy. Now when pulling her horse trailer the interior lights will not come on unless the truck is turned on. The trailer doesn't have a on board battery. I check fuse 315? Battery charge and it was blown and swapped it with another just to check it but still didn't. Are there any other things other than the plug I could check and what is this battery charge relay?

The ford system is designed to cut the power off when the truck is not running.


Prevents your truck from having a dead battery.


Suggest and highly encourage an on-board battery for the trailer. In fact it is law in most states.


How can the emergency brake work for the trailer if there is no battery?

That was my fault I wasn't thinking about that battery I was thinking about the battery to power the jacks and stuff.

So ford doesn't have a constant 12v when the key is off?

No they don't. But if you pull the relay and jump it out you will. Mine is jumped on my 13 because having it off when the key is off doesn't work for my needs. You can't leave the trailer lights on all night and expect the truck to start, but if you use your head it's no big deal (and as you found GM and Dodge don't feel this is necessary), and I have to agree.

Yeah, only the marker lights will work with the power off on the truck.

I would think that if you do have onboard power that
LED lighting would allow you a lot more run time and
not have you come back to a No-Start truck after an
over night lights on.

Then there is this http://www.google.com/url?q=http://w...mnnYfnmpKLRJjA

Nothing like a timer to turn the lights off. Looks like an easy install
and with LEDs WOW.


Sean https://www.ford-trucks.com/forums/p...ctureid=149188

Which pins do I need to jump on the relay?

Been a while since I did it, but I think the relay was labeled normally if I remember correct. That said, pull the relay, look at the base of it and it should show markings at the pins (85, 86, 30, 87, 87A). You want to put a jumper between 30 and 87.