I own a 2006 3500 dually D-max & tow my 28ft.haulmark trailer very often,everytime the truck & trailer running light go to turn on(@ Night obvioulsy!)-it blows the 15amp fuse under the hood-I still have brake lights & turn signals though.
I put a BIGGER fuse in & it just pops that also-I just drove home tonight from the track(again) with NO running lights & am sick of it!:mad:
Back in March I went to Florida & left from here in MD In the freezing cold with Ice & snow & everything,on the way home back home from Florida is when it first started this-Like corrosion or something?
I have hooked 3-other trucks to the trailer(1-Ford F250, & 2-other duramaxs)& NO fuses blew on these trucks-which leads me to beleive its my truck & NOT the trailer........Any or all help would be greatly appreciated-Thank you........Chris Evans

Bigger fuse is not the solution. I think you have a dead short...and are gonna have to trace it out.

Check the trailer plug for the greenies, then I would get a new trailer plug, follow the diagram on the truck plug and wire a light up to test the running lights to ground, use a big flood light or fog light so you get a amp draw, if that works, then start looking for a short in the trailer code, and work your way back. My 01 plows snow, iots out in the crap all the time, no issue to date on the truck, but trailer wire jobs are very cheap...

Greenies?Not sure I follow? Also-where would the"dead short"be-in the truck? I don't beleive it is the trailer......cause I have hooked other trucks to it-with NO problems.
I was thinking of trying a new 7-way plug.....Maybe?

Greenies = Green crap that builds up on the copper pins

Possible your trailer is wired fine for the other trucks but not this one, so when runing lights come on they hit ground and direct short. Check wiring diagram of trailer against truck and make sure everything checks out. If it does, disconnect the lights and see if the fuse still pops. if it does then you know the problem is between the plug and the lights.


:thumb:
Denali

Shady50,

Try this website, www.marksrv.com/wiring.htm. It will let you look at the connectors and identify the wires. Either your trailer or truck has probanbly been (re-engineered) sometime along the way.