I drive a 2017 f150 xlt sport
I’ve been dealing lately with the typical Minnesota weather, 9 inches of snow one day, then 42° temps the next and I live on a gravel road so everything is a mess. About a week ago, I had 6 inches dropped on where I live and when I drove around in the snow, water, or wet gravel roads, my truck constantly dinged at me saying “Connected trailer” and then “Disconnected trailer” and sometimes “Left (or) Right trailer lamp faulty, check lamps.” I don’t even have a trailer hooked up to my truck. This only happens when I’m driving in wet or snowy conditions, never when it is dry out. I just bought it this September so I still have a warranty on it and it only has about 6500 miles on it. If anyone could tell me what is wrong I’d greatly appreciate it, but whatever is happening is frustrating me badly.

 

I would start by checking the trailer light plugs to see if they're dry. If there's moisture in there, combined with freezing and thawing, it could make the truck think a trailer is hooked up.

Spray some compressed air in there, then some WD40. Then make sure that the covers close properly.

 

Also check the wiring behind the trailer plugs. From the sound of it you might have a frayed wire or two that is acting up when snow/water/salt/dirt gets sprayed up behind the bumper.

 

Good call. Or the harness may not be solidly clicked into it's connection.

 

I checked in the trailer plugs and they are spotless. I checked the wiring behind the bumper and that looks fine too. Is there any other trailer sensor on a pickup like mine that would be sensitive to water, mud, or snow? I pulled trailers all fall this last fall and the lights on each trailer worked perfect and I never had a problem. Again it’s not that I have a trailer on, it’s flashing at me saying I do when I actually do not.

 

 

If your truck is still under factory warrant I would recommend letting the dealer service department fix it. That's what the warranty is for. If you try fixing it yourself Ford could possible never find out their is a problem.

 

Try to Delete Current,or Active Trailer in the Trailer Menu maybe that put a glitch into the system to keep the Warning from popping up I had to do that a couple of times.

 

I am in MN driving in the same exact conditions and have not had any of these problems. Have you modified your trailer wiring at all? It is very sensitive to changes like using it to power aftermarket lights or a topper.

 

I have a 2018 F150 with 600 miles on it and it started doing the same thing this AM. I live in Florida. No trailer attached.

Op did you ever correct this issue?

 

I have had this issue and learned a few things.
1. Go into trailers and make sure you do not show a trailer connected. If you do disconnect it and it will likely resolve your problem. Not it try step2.
2. If your TRAILER has all LED lights and no other draw you need to do one of two things. Either change the settings in forscan to lower numbers for detection (I cannot help you with this as I would not do it because I tow trailers with both light types) or add a resistor kit to left, right, and running on the LED trailer. I didn't have to put one on running because I have a reverse camera as well. You can find them cheaper but here is an example
https://shop.advanceautoparts.com/p/sylvania-led-load-resistor-hyperflash-solution-loadrbx2/11137849-p?c3ch=PLA&c3nid=11137849-P&adtype=pla&gclid=Cj0KCQjwnZXbBRC8ARIsABEYg6BFe2y xWv0qO0s7CkQsdpe6GmJ7SOcRwsQdF3wei2f2Tk1A0ExLzaYaA mpKEALw_wcB&gclsrc=aw.ds
3. If none of the above are your problem and you tried cleaning the connector with no help may e some dielectric grease in the connector and under the truck on the wire harness.

good luck and I hope you get your issue resolved.

 

I have a boat trailer with incandescent 1157 tail and small incandescent side marker lights. One side light broke and am considering replacing with a 6 LED sidemarker. Will this mess up the trailer detection bulb warnings by mixing them?

 

Unknown. Our travel trailer has all LED tail, stop, and marker lights, and we do not have this issue. Our old utility trailer has conventional incandescent tail, stop, and marker lights. When one of the front marker lights got broken, I replaced the front two markers with LED, and we still did not have this problem.

 

no. One regular bulb provides enough resistance that you don't need to add anything. I have all LED running lights but because I have a backup camera it pulls enough current to let the truck know the lights are working.

 

I have all LED's on my boat trailer with no other draws, and the truck functions fine. It knew when a blowout caused one side's turn/tail light to become unplugged. Ford has to know that most trailers are only going to have LED's these days.