Running lights

[Jaybird]

I am pulling my trailer with a '94 F250 7.3

I am having a bit of trouble with my running lights. Ever time I install a new fuse in the truck, it blows. Am I going to have to pull the harness from under this thing and find the short? Is this a comman problem with an easy fix?

Just as a side note...just after I found out my running light fuses blew the first time, I decided to get my trailer home using the flashers....to my surprise, when you engage the flashers while in overdrive, the tranny automatically shuts off the overdrive. My buddy says I imagined this, but I assure you it does. Did y'all know this?

 

[Patman]

Check the plug connection at the bumper first it's VERY possible your problem is corrosion of cracked wire(s) at one of the trailer plug ins. Check both as they have common wires.

 

[Jaybird]

That was my first look, since it was the easiest. Everything in-tact and looks to be fine.
The fuse blows without the trailer connected.

 

[BSWIFT]

The Flasher/overdrive is connected. Ford's have done this for many years, safety issue.
BTW, does the truck blow the fuse when the trailer is not connected? If it is ok without the trailer, the connector is a likely culprit like Patman suggested, next is to check the trailer wiring. What type of trailer?

 

[Jaybird]

It's in the truck, Brian.

 

[BSWIFT]

After checking the plug, check the light switch on the dash. I have seen these go bad and do strange things. Do a visual inspection of the wiring from front to back underneath the truck. My work truck had the brake lights go out and it was from some road debris kicked up and grounded the hot wire to the brake lights. Could be that simple.

 

[Jaybird]

The front to back thing is what I expect I will have to do.
But hey, with a quarter of a million miles on the truck, one can expect a little trouble from time to time, huh?
:)
btw...I don't think it is the switch. The running lights on the truck work fine, it's just the auxillery that isn't working.
The brake lights, flashers, and turn signals work fine on the trailer too.