5th wheel power harness?

[KenJ]

Hello,
Recently purchased a new to me F-350 to tow my Sundance 2900MK. I have noted that when I connect the truck to the trailer There is no power to the trailer unless the trucks engine is running. This was not the case with my older truck. With that truck, when the power harness was connected this didn't happen. there was always power to the trailer, engine running or not. Of course this means that if the trailer battery runs down I cannot get power to the coach unless the truck engine is running. Not good for the neighbors nearby. Does anyone have any idea as to what might be wrong?

Thanks Ken

 

[RoadJunkie]

I believe that on my 2015 truck only the key must be turned on to get 12Vdc, truck doesn't have to be running. I don't recommend running your trailer this way because all sorts of other demands are enabled on the truck when the key is on.

 

[KenJ]

I believe that on my 2015 truck only the key must be turned on to get 12Vdc, truck doesn't have to be running. I don't recommend running your trailer this way because all sorts of other demands are enabled on the truck when the key is on.

Thank you but shouldn't I be able to have 12vdc with the trailer connected to the truck without running the engine or turning the key on?

 

[jnbhobe]

I think 12V power goes threw relays on the newer trucks so the key has to be on.

 

[rhodies1]

Thank you but shouldn't I be able to have 12vdc with the trailer connected to the truck without running the engine or turning the key on?

I have a 2012 F350 and the key must be in the on position to get power to the trailer.This is a feature Ford has put in place so you do not killl your truck batteries,it is different than a Chev. Ford is Key on-power on .

 

[Oregon_Camper]

I guess if you want this to work you're going to have to rewire that circuit to the back of the truck

...or...

You can purchase another 7 way receiver plug and wire that to your battery. Mount at front of your truck and then you have 12v power from your truck to you RV via the RV's umbilical cord whenever you want it. Easy...$15 mod gets you what you want.

Truck manufactures don't always know what is best for us....sometimes a little modification here and there work out.

Link to receiver on Amazon.

 

[Lynn1130]

I think the idea of unswitched power to the trailer is there so that you do not run the vehicle battery down should you remain hookup for some reason. This would be especially important in situations like I have were I an dry camping for long periods, hook up power, not start the truck, and leave it hooked up while getting ready to leave. It would not take long for the low batteries on the trailer to bring the truck batteries down, and perhaps not allow me to start the truck.

 

[SLO]

I have a 12 Ram. I was surprised it gives constant power to the trailer. My older vehicles were always wired through a solenoid. Wish my Ram was not constant power, but I never fixed it.


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[KenJ]

I have a 2012 F350 and the key must be in the on position to get power to the trailer.This is a feature Ford has put in place so you do not killl your truck batteries,it is different than a Chev. Ford is Key on-power on .

Thanks!! That's the same truck that I have. Does the key go accessory or run position?