DavidGK

Just took home a 2016 F150 EB XLT with max tow package.

Wouldn't you know it the aux circuit isn't hot and of course the Dealer is pretty clueless. (If I was as clueless with my clients on my services I won't have any.)

The owners manual is useless. None of the listing for the fuse block indicates which one might be the aux circuit nor what amperage to use.

Has anyone hooked up the 12v aux (for charging the trailer battery) and know what fuse block number and what amperage I need?

We are leaving town tomorrow so quick answer is appreciated....Thx.

smokeywren

So you don't know how to read a fuse/relay diagram?


On mine, it in the Owner's Guide under "Roadside Emergencies", then "Fuses and relays", then "Power Distribution box". The power distribution box is under the hood, near the radiator. Position #6 is "trailer tow (TT) park lamp relay. # 9 is "TT battery charger relay". Position #21 is a 30-amp fuse for "TT battery charge relay power".


You must have both the fuse and the relay for the 12-volt wire in the trailer plug to be "hot", And it's hot only when the engine is running.


Your newer pickup may be different, but I'll bet the fuse is 30-amp.

DavidGK

According to book 9 and 21 are blank. I called the dealer and he went out and looked at another truck and low and behold there are no fuses in glove box for this purpose like in 2015< and he confirmed 9 and 21 are blank. So dealer service is clueless. Something changed for the 2016s.

I found this video and beyond getting that circuit hot there is a bigger issue of wire size and max amperage.
Apparently Ford has decided folks no longer really want to tow their travel trailer with their $45K MAX tow package.....I'm more than slightly annoyed at this point given the first thing I have do on my expensive new truck is a wiring harness mod.

DavidGK

So took the truck in to dealer and they put it on their "tester" and the pin is hot.

For those reading this here's the deal. When you plug in your trailer must have a "chargeable system" on pin 5 (12v Aux pin across from the ground) in order to trip the "TRM" module which in turn puts 13+V to that pin. In Pre-2016 you just popped in the two provided fuses and you were good to go..like the other poster says that pin is hot.

The rub is hooking up the trailer to the vehicle I just traded in was fine but this doesn't "feel" as though my trailer battery is a "chargeable system" so it doesn't light up.

I'm kinda stuck at this point. I do have a low voltage preventer in the trailer that keeps the trailer battery from drawing from the car when the car voltage is lower (i.e the car is off). That's pretty standard device that's maybe messing with the "chargeable system" requirement.

So anyone have bought a new 2016 and had this issue let me know. Thx

Steve Osborne

yes the pin is hot.. only once active in programing ---adding to trailers read up on the programing.. and back up assist if you have it..

there are post's on the charge circuit---its not great----charge your batteries before--the trucks wire is small-not able to handle large load/charge capacity....some have added a relay and wired up a heavier guage to the trucks battery and use the circuit to activate the relay to allow a larger load/charge..

https://www.f150forum.com/f82/chargi...349231/index2/

https://www.f150forum.com/f82/wiring...353398/index2/

DavidGK

Had already programmed in the trailer, battery is already charged still no love.

Anyone had issues with something in the trailer circuitry that kept truck for seeing a "chargeable systerm"?

Steve Osborne

once programmed....and then you unplug and use another and un plug the truck will sense this ---trailer disconnected...each time you connect another trailer you will need to select the right one and cycle the brake to get the charge circuit-I have 4 trailers...2 need battery/charge--part of the smart battery/maint circuit......lmao.....it will only do what it see's.....and have you had the battery-batteries tested...if the smart battery system of the truck see's it full charged it will shutdown...lower voltage...its a stupid part on ford for this new system..
I want lights in my trailer or I need to charge my battery...

hondo2016

Steve,

why isn't the 4 wheeler behind the boat? I could just see the troopers in New Jersey having a complete fit when someone is pulling that road train down the turnpike... they'd have to charge you with something!

Steve Osborne

the o.p.p. and m.t.o are idiot sticks here...plus the rv part gets you out of the 3/4 ton/yellow sticker b.s..and I never go to the states....since my 20's to new York... that was enough...

hondo2016

Steve & David,

here's what I'm doing... the guy with the red F150 had a great idea, except he spliced into his factory OEM harness. I didn't want to cut those wires on my 3 week old truck. the dealer said you need to connect a battery in order for that circuit to be live. they call it a +12 vdc but it's only a battery charger (5 amp fuse under the passenger floor board area. instead, i bought the jumper that RDB83052 (red truck video guy) recommended and then began searching for the other end. eTrailer recommended a $60 5th wheel harness to rob the connect or from, walmart had my solution for $22 and northern tool had it the day I wanted for $28. so I am joining those two connectors together (see diagram) and simply routing that 7th wire, directly from the PK 11998 connector to the truck battery (passing through the 20 amp break like RDB83052). Steve, if you'll recall, my end goal was led lighting on the bumper and the trailer but the same configuration will allow the alternator to charge that trailer battery as well as the truck battery as RDB83052 wired it.