So I have an issue with my trailer plug. It is the round 7-way plug. I have all lights working properly on the Excursion and the trailer backup/aux terminal, trailer running lights terminal have 12V DC. My problem is that the trailer LH turn/stop and RH turn/stop do not have voltage to the plug on the Excursion. Both wires in the plug (when hazards are on) "flash" but with 0V DC. I checked all the fuses and relays both in cab and under hood and everything checks out fine.

Another point I think that makes this even more of a headache is that all lights have worked fine on this trailer and others I have towed before.

 

Ground ok?

 

You need to start by checking every fuse under the dash and under the hood, use a little electrical probe tester in the 7 point plug to verify they all have power (One of them will be a ground), mark each contact with an initial and marking pen (LB is left blinker etc), make sure all the lights etc are working on the trailer, then match up the male and female plugs and contacts but make sure the ground is good and trailer should be hooked up also.

 

I have already checked all the fuses in cab and under hood; they're all good. I have already checked the terminals at the plug and I know which terminals are which. The ground is fine. I unplugged the extension to the plug and the story is the same at the main plug. I am seriously lost here.

 

That truck has a lot fuse fuses, take a look at the owners manual or download one and doublecheck every fuse. Most ot the ones for the trailer plug are under the hood. I am assuming you don't have juice to all the contacts in the plug. Doublecheck all your fuses then you might have to start probing wires with the probe but I doubt if it will come to that.

 

recheck 7.5 amp fuses in power distribution box under hood. fuses 20 and 22. These are trailer tow RH/LH turn and stop lights.

 

The trailer light fuses are separate from the Excursion light fuses. They are located under the hood, driver's side.

 

Well; I thought all the wiring was good and apparently the turn/stop wire doesn't flash to 12V DC when it powers the lights.

Fixed the problem. It turns out it was shorting out in some old wiring at the lights so I ran new wiring all the way down the trailer to the lights.

 

We thought you had the problem in the truck, trailers always have short problems.

 

I thought it was on the truck too. When I checked for voltage on the LH/RH turn signal terminals it came up as 0 volts but it would flash each time the hazards on the truck would flash. But then I just ran new wires all the way back and everything worked just fine. Only thing I don't get is why it still shows 0 volts even when the lights light up. Oh well. Thanks for all the help on a problem I didn't have haha.

 

I have problems with the pigtail that connects to the back of the harness on the truck. I will unplug it and clean it out and it will be good for a while, then it does it again. May be time for a new one haha.