Trailer wiring changes?
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2nd Gear
Joined: Nov 2023
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Trailer wiring changes?
I’m sure this issue has been addressed somewhere, so if it has, please point me there! My husband and I just took delivery of our new 2023 SuperDuty and realized yesterday that the 7 way trailer plug does not work with our trailers - an older horse trailer and a flatbed trailer. On the horse trailer we were able to get brake lights and nothing else, and on the flatbed only running lights. All lights and trailer brakes work correctly on both trailers when hitched to our 2010 F-150. Has something changed with the wiring since 2010? We need to be able to tow both trailers with both trucks, and also the occasional trailer we might borrow.
Hotshot
Joined: Oct 2015
Posts: 19,726
Likes: 12,873
From: Wyoming
Make sure you cram the plug all the way into the bumper outlet. Check the back side of the bumper outlet to see if the wiring on the back side is well connected. There was at least one forum member that had loose wiring on the back side.
The truck won't send 12 volt power to the trailer battery (if you have one) unless the engine is on and other criteria are met, like pressing the brake or putting it in gear. The criteria seems to be different over the past few years, so you may have to experiment.
The truck won't send 12 volt power to the trailer battery (if you have one) unless the engine is on and other criteria are met, like pressing the brake or putting it in gear. The criteria seems to be different over the past few years, so you may have to experiment.
FTE Remembers
Joined: Jul 2005
Posts: 65,938
Likes: 1,432
From: Millersville, MD
Also check out the trailer wiring so it matches the diagram here: https://www.ford-trucks.com/forums/5...g-diagram.html
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2nd Gear
Joined: Nov 2023
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Ok thank you everyone! When my husband contacted the dealership about it they said there was a change in 2018 or so and the truck was correct so they wouldn’t even look at it and we would have to redo the wiring on our trailers, but that just didn’t make sense. These are just basic, old trailers, they don’t have batteries or anything, but have decent wiring. It is frustrating that everything works fine on the old truck and not the new one.
Cross-Country
Joined: Sep 2023
Posts: 52
Likes: 39
Ok thank you everyone! When my husband contacted the dealership about it they said there was a change in 2018 or so and the truck was correct so they wouldn’t even look at it and we would have to redo the wiring on our trailers, but that just didn’t make sense. These are just basic, old trailers, they don’t have batteries or anything, but have decent wiring. It is frustrating that everything works fine on the old truck and not the new one.
Hotshot
Joined: Oct 2006
Posts: 10,188
Likes: 8,071
From: Texas
I’m sure this issue has been addressed somewhere, so if it has, please point me there! My husband and I just took delivery of our new 2023 SuperDuty and realized yesterday that the 7 way trailer plug does not work with our trailers - an older horse trailer and a flatbed trailer. On the horse trailer we were able to get brake lights and nothing else, and on the flatbed only running lights. All lights and trailer brakes work correctly on both trailers when hitched to our 2010 F-150. Has something changed with the wiring since 2010? We need to be able to tow both trailers with both trucks, and also the occasional trailer we might borrow.
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FTE Remembers
Joined: Jul 2005
Posts: 65,938
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From: Millersville, MD
Did you check out the wiring on the trailer as I asked you to do in my post above? Simple check to see if the wiring between the truck and the trailer is the same. If you do not have the ability to do this, take it to an RV repair facility to have them test / repair it.
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FTE Community Team
Joined: Jan 2019
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Yeah, the wiring has stayed the same for decades. It's possible that the new truck has a defect, but it is unlikely. Best bet would be to get out a test light and test each mode at the receptacle . . . then troubleshoot from there . . . or take to a good shop if that's the best option.
Hotshot
Joined: Oct 2006
Posts: 10,188
Likes: 8,071
From: Texas
To expand on my previous comment. I “THINK” modern, late model trucks have to sense that there is a complte circuit before the said circuit is activated in the truck. If, for any reason, the circuit is open there won’t be any power going to it.
Therefore one need to make sure each and every circuit, along with every light on the trailer is properly grounded.
Almost ALL trailer lighting problems ultimately go back to poor groundfing.
Therefore one need to make sure each and every circuit, along with every light on the trailer is properly grounded.
Almost ALL trailer lighting problems ultimately go back to poor groundfing.
Fleet Mechanic
Joined: Jan 2023
Posts: 1,346
Likes: 461
To expand on my previous comment. I “THINK” modern, late model trucks have to sense that there is a complte circuit before the said circuit is activated in the truck. If, for any reason, the circuit is open there won’t be any power going to it.
Therefore one need to make sure each and every circuit, along with every light on the trailer is properly grounded.
Almost ALL trailer lighting problems ultimately go back to poor groundfing.
Therefore one need to make sure each and every circuit, along with every light on the trailer is properly grounded.
Almost ALL trailer lighting problems ultimately go back to poor groundfing.
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