Does 12 Volt Circuit of Trailer 7-Way Have to Be Connected

Question:

I replaced the pigtail on my fifth wheel that goes to the truck. Pretty simple as all the wire colors matched. However, I am wondering about the black 12v battery wire. It wasnt connected to anything, just had a cap on it. What is this for and should it be hooked to anything? Or is it just an auxiliary power source?

asked by: Gene

Expert Reply:

The 12 volt auxiliary power circuit of a 7-way is not always needed/used. If you don't have anything on your trailer that needs this circuit like a battery or a set of auxiliary lights you can just cap it off and not worry about it. If you wanted to complete this circuit though you'd need 10 gauge wire like part # 10-1-1 (sold by foot) and a circuit breaker like part # 9510 to run it to your truck battery.

expert reply by: Jameson C