2013 Ram 5500 Trailer Wiring | etrailer Fastest shipping available and a lowest price 2013 Ram 5500 trailer wiring guarantee. Expert lifetime technical support on all purchases. Complete 2013 Ram 5500 Trailer Wiring installation instructions and customer reviews. Call 800-298-8924 to place your order or order online at etrailer. Trailer tow wiring for the 2013 and 14 trucks | Turbo wwwodieselregister››4th Generation Ram ArchiveMar 07, 2014So if the trailer is plugged in with the truck turned off, you are still send 12V DC to the trailer battery. Even my 93 and 2001 Dodge RAMs were set up this way. Using a lot of power in the trailer, say at a Walmart over night and you are pulling charge from the trucks batteries in parallel with the trailer battery.