I've found a problem in my truck's wiring. It's going to drive me right around the bend. I've recently bought an enclosed cargo trailer. I, of course, did a light check on the trailer. All lights work except the left brake light and left turn signal. The left tail light is fine, and all lights work on the right side. Running lights and such are good. All lights are good with that one exception. The jack on the truck is a 7 pin round traditional, flat pins. This style is dictated by the jack on the trailer. The trailer has electric brakes. The flat pin for left stop and turn light is dead, never receives power. Sounds like a simple fix, right? I call BS. I've checked all fuses, both under the dash and in the engine compartment. I pulled them all and tested with a multimeter. All fuses are good. I opened up the jack under the bumper looking for a loose connection. There was none. A point of interest here. The power distribution box, fuse box, under the hood seems to be from a '94 truck, according to the diagrams I've found. It has a different layout from what I was expecting. My truck is a '92, built in 11/91. What am I missing? Is there some place else to simple turn off that circuit? Can you tell how much I dislike automotive electrics?