Hello my fellow ford gurus I have a 2000 F 250 with a trailer towing package on it that I am having trouble with. The towing plug at the back bumper has had trouble in the past where you would have to wiggle it to make the clearance lights work on my travel trailer. I had to get the trailer inspected for the licence plates the other day and at the station the clearance lights worked but the blinkers didn't. We wiggled the plug again and the blinkers worked but then the clearance lights stopped working. The guy was nice enough to go ahead and pass the inspection if I promised to replace the plug. I purchased the new plug with wire harness just to plug into the the factory harness and have no lights at all now. I have one hot wire that is working in the plug but no blinkers or electric brakes nor clearance lights. I used a test light on the wires from the plug to the engine compartment and only one wire worked with the blinker on in the truck. I have all lights working on the truck. I replaced the two relays and fuse in the fuse box and the little factory brake box on the side of the large fuse box but still not a thing. Anyone out there got any feed back on what is wrong or what else I could try?

Thanks in advance,
LW Brauer

 

I have found that each of the 6 slots the truck 7 pin connector expand when used multiple times over the years. Their "clapping" force lessens over time. I have taken a small flat blade screwdriver and pried each side of the female sides to close them up so the blade of the trailer connector will make contact and be held firmly.

 

I would hook the trailer to another truck and test. At least that will tell you if it's the truck or trailer.

 

Just Strokin I have done that before I got the new plug and it made no difference. The only difference it made was making it a little harder to plug all the way in. It has to be something else as I said I have no power to the wires that go to the plug on the truck. Used a test light and probed the wires from the front of the gas tank back and no power except for the red large wire which is suppose to be for left turn and stop but no others.
Thanks for your answer.

 

The mice loved to chew the wires on my 2000 due to the soy based wire coating I was told that was used. Caused sporadic and strange things to happen. No headlights, one headlight dim, one blinker not working, not all at once but on specific times. Ford was alway able to find and correct the problem, for a fee of course. Not saying the rodents got to your truck, but all of my electrical problems were caused by them.

 

Street rodder I plan on hooking it to my wifes SRV tomorrow and see but I am already sure it isn't the trailer as we pulled it with wifes SRV last trip and everything worked fine.

Thanks for the answer,
Larry

 

you have a wiring problem of some sort it seems. as suggested, plug trailer into another vehicle and another trailer connect to your truck to see if you can isolate which side the wiring problem is on.

Have you tried tightening the screws/lugs on the back side of each connector to make sure you have a good connection between the plug (male or female) and the wiring of the trailer or truck.

 

Bugzilla46310 that is a thought but surely they didn't chew all the wires at the same time. I guess it is a possibility though. It is just funny that all the lights on the truck still work just not the towing plug. I have removed the plug wires out of the wire loom from the back of the truck to the front of the gas tank and see no brakes or chew marks. I know ford could probably find the problem but I don't have the $600 + dollars to spend right now.

Another great answer thanks,
Larry

 

Just Strokin I have checked the screws on both plugs also. I just couldn't find the problem so I purchased a new male and female machining plug and put it on still no jouce.

Another great answer thanks,
Larry

 

When ever trailer lights do wierd stuff, check all grounds, check all grounds, and check all grounds! Most likely you have a poor ground "someplace" in your system.....either the lights are not grounding to the trailer frame properly, or the trailer is not grounding to the tow vehicle properly....but lights to trailer frame would be my first guess! Good luck!

 

What 99150 said, whenever I have run into issues such as these where everything seems to check out, the ground wire is loose or the contact needs to be cleaned.


I was pulled over by an Oregon state trooper one time for no trailer brake lights (while pulling with my 77 F150). I jumped out and after quickly testing the wires saw that the ground wire was loose. after tightening it up i was on my way and thankfully ticketless.

 

I had a similar head scratcher awhile back. It was the lowest wire that connects to the truck harness. I assume that a rock hit it. It broke that wire inside the jacket and was intermittent. I believe that is the main ground connection.

I disassembled the connector, stripped the wire back to good copper and reassembled the connector. All has been well since.

 

My E-350 had trailer issues and it turned out to be a bad Auxiliary battery under the van.
I installed a new battery and went on my way, after spending a lot of money on testing.

 

Thanks guys for all the feedback on the trailer wiring. This is what I have done so far. I have hooked my wife's SUV to the travel trailer and all the lights work well blinkers, stop and clearance lights so I know it isn't the trailer that has the problem. I crawled under the truck and unplugged the wire harness that the bumper plug is plugged into. I used a test light to see if I was getting any power there and I had only one wire hot which was the electric brake wire. No running lights nor blinkers. I then from there took all the wire loom off the wires that run along the frame of the truck from back to the fire wall looking for a broke wire or a loose ground. I didn't find any and then I poked the wires all the way up every two to two and a half foot with the test light and didn't get any fire except for the electric brake wire. I then went back and tested each fuse in the fuse box under the dash and under the hood in which they all were hot on both sides so they are all good. I changed out both trailer towing relays under the hood and still nothing. I am stumped to high heaven. We are leaving tomorrow morning and will be gone for a week so when I get back I guess with great dismay I will have to take the truck in to either the dealer or a mechanic and see if they can figure it out.

 

are there trailer-specific fuses that you checked?