12v to trailer turns off when ignition off

[jonwright]

Anybody else have an issue with that? In our trailer I have 12v interrior lights that run off of the truck. It would be nice if they worked when the ignition is off.

My buddy's DODGE does that.

Any tips on where/how to fix that? I'm not really sure even where to begin.

 

[F350DRW1]

Anybody else have an issue with that? In our trailer I have 12v interrior lights that run off of the truck. It would be nice if they worked when the ignition is off.

My buddy's DODGE does that.

Any tips on where/how to fix that? I'm not really sure even where to begin.

Get a test light and find the trailer harness wire that is always hot. Find interior of trailer wires [should be in junction box if trailer is a quality unit] and splice. Not a bad idea to run a circuit breaker in line on this new circuit you are creating. I ran mine to the hot side of my electric mast jack. Took more time to find wires than the rest of the job did. Outside indicator is also a good idea, because now you can leave trailer hooked, and drain all batteries if lights are left on or if cargo accidently hits switch. Good luck.

 

[powerboatr]

not sure what year of truck you have, but most are designed that way.
the 7 pin connector doesnt have a HOT line all the time, you would have to wire one in.
but its set up so you dont run the batteries down if like was mentioned the cargo flips the light on, yep its a PITA i had to unload my cargo with the truck running at night, just to see.
sort of makes you nervous hearing the truck run the trailer vibrate , all the while knowing th ee brake could pop off and she jump into drive, while your bouncing around out back

like f350 mentioned you could splice into your HOT wire on your trailer battery, but again you could have a dead trailer battery if the light gets left on.

you could set up a relay on a timer, so after XX amount of time it cuts off

 

[dboyw]

I had this exact problem. Here is how I fixed it. I took a piece of 10g wire, I think that was the size, put two spade terminals on either side, covering whole thing in shrink wrap, and put in place of the relay under the hood.

Here are the pictures in my list.

If you have questions, let me know.

 

[W4RLR]

Robert is right, it is purposely designed that way. Can you imagine what would happen if you left the 12 volt load of the trailer on when the truck is not running for more than say, an hour? It's quite possible you would not be able to start your truck if the load was high enough. If it's just a light bulb or two, you could get by. Some people wire their entire 12 volt trailer accessory buss to that one hot wire from the truck. It can drain a set of batteries quick!

 

[97CREWCABPSD]

put a battery in the trailer the way it was designed and dont mess with the truck.

 

[F350DRW1]

put a battery in the trailer the way it was designed and dont mess with the truck.

Yeah, I agree. I wired mine to the trailer battery.

 

[iracemine]

Howdy.

My truck did not come with that trailer charge relay..... How much and where do you think I can pick one up???

 

[iracemine]

for future reference for those like me. it was just a multi purpose relay 40 amp from pepboys for 2.99. it was the forward of the two slots made the charge wire and a 30 amp fuse in the under hood fuse block work.

also at pepboys I found the same electric break a way system for 40 bucks less than what I bought it for at the trailer shop.

 

[Ezzie]

I am thinking of installing a battery inside the trailer to power the 12V trailer lights and an inverter for 110V AC for other misc. uses (like an AC radio). Could I just use one of those battery isolator units they use for RV's to tap re-charging current from the trailer harness going to the truck? This way it would re-charge the trailer battery when the truck is running only. Would anyone have a wiring diagram for something like that??