Hi Albert, Well, to begin with, David is right, the towing lights, i.e. tail (and running lights), stop, turn, and backup....all the ones that operate from your car/truck etc, are completely separate from any interior electricity....or the "living in the camper" lights. These wires are all isolated and go directly from the umbilical cord to the individual lights and to the brakes (if you are set up for that). Having said that, your system can be set up to charge the camper battery while towing. Also, in the event of the trailer coming unhitched while towing, the break away switch will connect the 12V
trailer battery to the brakes and lock them up.
In researching this, I've found several wire-color conventions for the 7-pin umbilical cord configuration. Thanks to Davids post, I managed to determine how my 1965
AS was wired. Note this may be different for your camper. So here's the color convention mine used:
Blue=Battery Positive terminal
Green=tail and running lights
Black=auxilliary or stop
My camper was configured with the integrated stop and turn circuit which is what most moderns configs are.....so the black appears to be aux, or unused.
As it happens, I am replacing the "nacelles" which are the big plastic housings into which the tail light fixtures are installed (on 1965
AS anyway). Contrary to the instructions on the website, I didn't have to remove the entire interior wall to install them. I just asked myself..."What would Houdini do?" So with a little creative trimming and a little ingenuity, I was able to slip them in from the outside and rivet them in without hacking up either the interior or the exterior walls. I also found a pair of "retro-designed" LED stop/turn/tail lights that replace my old fixtures quite nicely.
So...imagine my surprise when I removed the old tail lights and found black wires connected to the metal housings of the fixtures. I checked these wires with a meter and sure enough, they were indeed ground wires, but they were in no way connected to the black aux wire (U-cord) at the front of the trailer. But I didn't see any wires that did connect to the U-cord aux. Hmmmmm.
Sooooo.....when I removed the old cracked, broken nacelles and started digging around inside the wall, I found yet another set of black wires tucked inside. And these, much to my joy, were the missing aux wires.....just waiting for something to be installed. YeeHaw! My backup lights! And since I hate disorder, I replaced the black ground wires (the impostors!) with white wires and was able to thread them down to the steel trailer frame.
Now when you assemble everything, you need to make sure it's water proof and mouse proof. Also you don't want any shorts to develop. I'm using rubber grommets where ever the wires pass through metal walls and you want to make sure the whole thing won't fall apart over time. Remember, a trailer goes through a lot of vibration while traveling.
I replaced all the rivets that I drilled out and used putty between the riveted surfaces and silicone where needed and I used Vulkem generously around the edges of the nacelles where they interface with the aluminum camper walls. My new tail lights didn't come with gaskets so I just cut a pair out of a 1/16" thick rubber sheet. Finally, I soldered all the wire connections and insulated with heat shrink wrap.
Well, That's all the news from Lake Minnetonka