379 trailer pig tail problems

Is it a portion of your running lights that are not working??? What make of trailer??? Van-Reefer-FB????

 

Look under the dash on the left side of steering column. You will see a black cable come from outside to inside that is your trailer harness. The older Petes are notorious for heat right there causing the insulation to be brittle and flake off, some times the wires them selves break, but usually just touch one another and throw a breaker. Also on the light switches they are bad to over heat and not make connection on the inside of the switch when turned on. First make sure you have power in to all three switches, them turn all three on and make sure you have power out of all three. One of the switches powers the black wire and some of the truck lights, the other powers the brown wire and the remaining truck lights.

 

Should be the first three switches on the top row to the left first is head lights the second two is markers. Sorry when I typed that I realized my goof, your right only two marker switches the headlights don't effect the markers.

 

my uncle had same problem.he ran a jumpper wire from the black to brown inside of pigtail and now all his works.i don't think i would use very big wire for jumper though.

 

While that will get you out of a bind, it is not a permanent solution. It puts the amp draw of 2 circuits on one which causes heat. The old breakers just don't protect like fuses do, I have seen many a switches justb melted down on the back because of this. But I'm sure it was done long ago and no problems, I just wouldn't chance it.

 

This will work, I've done that myself till I could get somewhere to get a new pigtail. As your looking at plug end take a piece of wire strip both ends of sheathing and put wire into #2 & #6 then plug your pigtail back in and all your lights should be working again. Remember this is a temporary fix.

This diagram may not be exact to yours but the position of jumper wire should go into same holes on your pigtail, diagram just to show you which ones to put it in.