I checked the voltage output at the plug and I get power to each prong on the truck except the left break/signal prong. I figure its a fuse but I cant find it. any help would be great. I need to tow a trailer 600mile this wed.

 

Are the truck lamps working correctly? On the older trucks, the left brake stop wire (lightgreen/orange) is tied into the rear harness at the back of the truck.

 

I found out that I have two fuses for my trailer lights one for the left and one for the right. and i had a blown fuse.

 

When mine did that it was a fuse under the hood near the master cylinder.