I have a 2001 F250 with the trailer package and have an issue with trailer lights. I have the 4 pin plug but when I plug any trailer into it I do not get running lights or tail lights. I do get brake, hazard, and turn signals. I also have the round plug which I tried an adapter that plugs into that and has the 4 pin plug on it and I get the same results. I haven't looked into it at all yet but just joined this site and was wondering is there a simple solution to this before I start trying to figure it out on my own.
Thank you,
Bill

 

I would go with the obvious, the trailer tow adapter parking lamp fuse.

Check it with a meter to both pins on the back of the fuse ( while installed ) to a known good ground.

 

So there is a separate fuse for the parking lamp? I havnt looked at all but wouldnt have thought it
had two fuses.

 

Would this fuse be in the in cab fuse block or at the back of the truck. This was a factory or dealer option, I am the second owner. I bought it in 03 with 29,000 miles.

 

Check your owners manual, page 177.

fuse # 8.

 

Thanks, I will follow up.

 

My owners manual is for an 04. When I bought my truck from the dealer it was two yrs old with 29,000 miles on it but there was no owners manual. When I asked for one the gave me an 04 and said they it was the same. Its not!!! Well I checked all the fuses as I have no idea which is which and they are all good. I dropped the spare tire and un plugged and re-plugged the harness and still no good. Does anyone know which pin would be for the running and parking lights or which fuse in an 01 F250. Just because the fuse is good, doesnt mean anything or does it go through one of the relays and maybe a bad contact. Im an elevator tech by trade so tracing circuits are no problem at all, but I need to know the circuit.
Thank you.

 

Did you have + VDC on both pins on the back of the fuse when you checked it with a meter ?
- Did you turn the key to the run position and turn on the headlamps to meter both pins on the back of all the fuses to call them all good ? Should have at least tripped over the high and low beam fuses and found 1 not working until you flipped the MFS to the high beam position.

Post #5 above I gave you the fuse number ( got it from a 2001 Superduty manual pdf version ).

If you need an owners manual ( in pdf version ) :
https://www.fleet.ford.com/maintenan...ls/default.asp

If the fuse is good, that indicates which way to diagnoses the symptoms, so it does mean something.

 

The only way to get to the back of fuse box it seems is to remove the whole thing which I tried to do but I think I was removing the computer as well. It does not want to come out. Im in a rush today so I will try again this week. I need to see if I can get the fuse box open without breaking it. I did check the fuse though and it is good, not that there cant be a loose wire or broken connection feeding the block. I wish there were test points or terminal blocks I could check it with. Do you know of a place where I can get an actual wiring schematic for the truck so maybe I can check voltage elswhere?
Thanks for your help.
Bill

 

There are test points on the back of the fuse while installed, not sure why you are making this more difficult than it needs to be.



That is why those 2 metal pins are there.

 

My bad. I never realized you could just check this type of fuse like this. Sorry about that, good lesson. Anyway, I have 14vdc on each side of the fuse so I do have a good fuse,connection and voltage at that point in the circuit.

 

Heres the update. I bought the book with all the wiring diagrams and traced it to a blown fuse. I was not aware that there is a fuse block in the engine compartment. The trailer running lights are a separate circuit which is protected by fuse #4 which is a 20A fuse and it was blown. Bought a new one and hooked the truck up to my neighbors boat trailer and we are good.
Thank you for the input.
Bill

 

I am having a similar issue with my 2005. My parking lights on the trailer do not work on any trailer using either the 4 pin or the 7 pin. My manual states that it is a relay in the engine compartment (R201). I am not an electrician at all hence I don't have the proper tools to check the relay to see if that is the problem. I can check and change a fuse no problem but don't have anything telling me what or if there is a fuse that powers the relay. Manual has turns, hazards and stop lights listed but nothing on parking lights. Thanks goes out to anyone that can lend a helpful thought.

 

I think they fall under running lights. Mine was fuse #4 under the hood. I will look in my manual and see if it is only for 2001. Can you post a picture of the page in the manual or email me a picture to billcaprio@optonline.net? Maybe there are test points or if the relay is removable and there is another one the same size you can swap it to see if it works then. I will look in my manual tonight and see if there is anything similar, my truck is an 01.