# rv plugs



## Guest (Mar 26, 2014)

im pretty sure on all 7 spade rv plugs on all heavy trailers with brakes have a 12 volt auxilery wire. im building a fuel trailer and need 12 volts for the pump. is there a good way of using this 12 v auxilery? or do i just need to run a new wire on the trailer plug?


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## NewBerlinBaler (May 30, 2011)

Not sure what you're asking bbos.

Your tow vehicle should already provide this on pin 4 (located at 7 o'clock when facing the tow vehicle's jack). It's the "trailer battery feed" and has 12 volts present whenever the key switch is on.

On the trailer side (if you're using a utility/flat bed), most likely there's nothing connected to pin 4 so you'll have to run a new wire to the trailer plug. This conductor is supposed to be black.

Gary


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## rajela (Feb 15, 2014)

I use the plug to run mt fuel pump in the bed of my truck. I put a 7 spade plug on the end of the pump cord and just plug it in when I need power. I used the aux power pole so I don't have to have the anything turned on to get power.


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## RockmartGA (Jun 29, 2011)

One thing to consider is the amperage of the component you plan to run. Something small like a fuel pump should be okay, but might want to double check to make sure you don't overload the wire.


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## Guest (Mar 27, 2014)

thanks guys

my tank will be on my trailer so id like to be able to just hook up my 7 spade cord into my truck and be good to go. so sounds like ill just need to add a wire to my trailer plug to my tank and be good to go


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## endrow (Dec 15, 2011)

RockmartGA said:


> One thing to consider is the amperage of the component you plan to run. Something small like a fuel pump should be okay, but might want to double check to make sure you don't overload the wire.


I agree on our Dodges and Chevys using the aux pin was no problem but on our
2000 F250 super duty it always tripped something and caused inconvenience's.


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## atgreene (May 19, 2013)

I always put a small battery on the trailer, then put a 10 amp circuit breaker in the power line from the truck. If the pump draws too much, it will kick the breaker, but run on the battery. Breaker will auto reset and charge the battery off the truck. I run everything from fuel pumps to 1hp electric motor (on my sander that doubles as an ash/lime spreader). Doesn't overload your trailer plug and yet allows you to keep the battery up. Also allows you to leave the unit and not have to plug it into a vehicle to get fuel, lights etc.... Breakers are cheap and can pop right into the existing breaker panel. Dellcity.com is where I get mine. Cheaper and easier than changing fuses or replacing burned plugs or wire.


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