need help wiring 7pin

[jeffw920]

i'm installing a 7pin rv connector in place of the flat 4pin that came with the truck. I'm all set on pretty much everything except one pin that asks for a 12v auxiliary line. From my understanding i can run this from the battery or splice in anywhere else i can find an always live 12v source (must be fused at 20amp max). My question was would it be better to go right from the positive terminal of the battery with an inline 20amp fuse, or is there a better place to tap in further back in the wiring harness? I looked at the fuse box diagram and found a 15amp circuit in fuse block 30 that says "trailer tow" or something to that effect in the owner's manual. Is this designated for what i need, and if so where can i tap into whatever wire that fuse is protecting?

sorry for the wordiness in the description, if anyone has installed a 7pin rv connector and has input as far as a good source for the 12v always on please comment

 

[timmy]

I ran a wire from the battery with an inline fuse on mine and it works great

 

[Snoranger]

Go right from the battery or starter solenoid bat terminal. Be sure to fuse it within 6" of the connection. Thats the best way to do it.

 

[jeffw920]

thanks guys, what gauge wire did you all use? ive been using 18 for everything else, but it seems a little light to me for something that is fused at 20amps.. will it be ok?

 

[kimcrwbr1]

20 amps is maximum overcurrent protection for you will probably never use that much power to blow the fuse. The best way to protect a circuit like that would be with a fusable link, For a 18g wire you want a 20g fusable link. one guage smaller on the link will keep that wire from lighting up from a direct short. Since the load for the circuit your adding is unknown I would go with a 16g wire with a 18g or 20g fusable link and for added protection run it through a relay so that circuit is only hot when the key is on.

 

[Snoranger]

I will always use 10 or 12 gauge, nothing smaller. You never know what youre (or someone else) is going to try to run off that. Plus you have to take into account the length of the run. I've always been a "do it right the first time" kinda guy.

 

[TomB1269]

I will always use 10 or 12 gauge, nothing smaller. You never know what youre (or someone else) is going to try to run off that. Plus you have to take into account the length of the run. I've always been a "do it right the first time" kinda guy.

+1, in addition the larger gauge will decrease the resistance in the line should you ever up a large draw on it. I have mine to the battery with a fuse link (ie the kind you can replace the fuse in) that is weather proof. The actual fuse always me to disconnect it from the battery when I am working on it. If I where to do it again and was will to drop an other $30 and the time I would have placed the circuit on a relay that would switch it off with the ignition. That way if I am hauling a trailer that has a constant DC load, IE fridgerator on board and running, when I stop for lunch or what not I would not have to remember to disconnect and reconnect my trailer (ie keep the fridge from draining the auto battery and let it run on trailer battery while stopped.

 

[TomB1269]

FYI; I would strongly urge you to pickup a seven pin multi tow vs a seven pin only, even if your only trailer is a seven pin. It is a hell of a lot nicer to have the 4 pin when needed, and a lot of the multi tows come setup to allow you to plug in your current 4 pin (less wire cutting, etc.)

 

[leviticus2629]

I will always use 10 or 12 gauge, nothing smaller. You never know what youre (or someone else) is going to try to run off that. Plus you have to take into account the length of the run. I've always been a "do it right the first time" kinda guy.

I have probably done about 100 or so 7way wiring jobs at work, and we always use 12 ga with a 30 amp fuse and have never had any problems, ever. If you use a 20 amp you will have no problems

 

[Sasquatch_Ryda]

I prefer to use circuit breakers rather than fuses for charge wires and brake controller wires.

 

[leviticus2629]

I prefer to use circuit breakers rather than fuses for charge wires and brake controller wires.

For brake controls I also use circuit breakers, for 12v line I usually give the option to the customer. It is always surprising to see how many people won't pay a few dollars more for a circuit breaker on their 12v line...

 

[Sasquatch_Ryda]

Well...I can't say I've ever given the option to the customer. Work order says "Wire in trailer wiring" then that's what I do, the exact same way I would do it as if it were my own vehicle. Plus I don't use a big honkin solenoid for the charge line anymore, just a 30 amp relay so ya save some money there.

 

[leviticus2629]

Well...I can't say I've ever given the option to the customer. Work order says "Wire in trailer wiring" then that's what I do, the exact same way I would do it as if it were my own vehicle. Plus I don't use a big honkin solenoid for the charge line anymore, just a 30 amp relay so ya save some money there.

yeah, I don't disagree with you, just saying that the way that I do it does work, I also don't make all the decisions in the shop I work at...

 

[wildbill23c]

Resurrecting an old thread, but I can't seem to find anything on a search that leads me to an answer. I'm getting ready to install a 7 pin wiring plug on my 84 Ford Bronco II, as the plug is heavier duty than the little 4 pin plugs that always seem to come unplugged somehow, anyhow, is there a diagram somewhere that says what wires go where on the rear of the bronco 2 so I know how to connect the plug wiring? I don't really want to pay a shop $90 to have it done.

 

[Sasquatch_Ryda]

So you want a 7 pin plug, but only need the function of a 4 pin? As in you aren't running a charge line or brake controller line?