Trailer Right Turn Lamp Fault

[Elabar4]

I am getting the same issue with my 2021 F150. Last week I picked up my new boat. The first day I had no issue with it other then my battery being dead the next day even with the trailer wiring disconnected. So I took it to the dealer on Friday and had the reflash performed for the battery drain. That day we took our boat to the lake and I started it get the light module fault and left turn signal fault. I tried a new trailer plug adapter today and got the same issue. When using my utility trailer I did not get this issue. Both trailers have LED lights so I do not think it is the resistance from the lights. The other strange thing is our running lights wi not turn off. I will turn the truck on and off a few times and they will go off eventually. Also our alarm just started going off on it own. Going to call the Ford dealer and boat dealer on Monday to see what they each say.

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[clipperqb]

I got this message today moving my boat around the driveway. It also happened a few months ago. The signal will flash rapidly in the cab but be flashing normally on the tail and trailer. Also today when turning on pro trailer assist it asked me to drive forward to initialize - I set it up weeks ago. Then a message that trailer is disconnected. The trailer is a 2021 with a prewired 7 pin blade connector. Guess I'll start by cleaning all connections. I know dealer would be zero help at this point.

 

[charmnh]

I got this message today moving my boat around the driveway. It also happened a few months ago. The signal will flash rapidly in the cab but be flashing normally on the tail and trailer. Also today when turning on pro trailer assist it asked me to drive forward to initialize - I set it up weeks ago. Then a message that trailer is disconnected. The trailer is a 2021 with a prewired 7 pin blade connector. Guess I'll start by cleaning all connections. I know dealer would be zero help at this point.

Same issues here. No dealer help.

 

[Moz]

Alright folks, I've finally found the solution to this.

I bought the 7 to 5pin adapter but in hindsight the 7 to 7 may have been more versatile as my existing adapter could in theory work between trailer and bypass.

7 to 5pin (4 pin can plug in leaving the aux power unused)

https://www.etrailer.com/Wiring/Tow-Ready/TR20141.html

7 to 7pin

https://www.etrailer.com/Wiring/Tow-Ready/20142.html

 

[IW500T]

I was having this issue intermittently on my 21 Lariat and putting some dielectric grease on the 7 pin plug fixed the issue and it has not come back.

 

[Nico]

Hey guys - just setting up my new Lariat PB to tow my Airstream...everything was good until I got this message. I checked all the Trailer turn signals and they both work fine when Im hooked up. Power to my Airstream's BT rear camera, trailer brakes, side marker lights and as mentioned the turn signal lamps. The truck recognized that the trailer was connected and did al the enabling/disabling of the different systems.

The message keeps coming up even after I acknowledge it by hitting OK. Sometimes it goes away sometime I have to hit the OK. Also took a picture of the plug on the F150 and the the 7-way from the Airstream. I am going to look up the 7 way plug diagram and see if there is something off...but everything works. Anybody have an idea?

I am having the exact same issue on my 2021 XLT

 

[dannko58]

Hey guys - just setting up my new Lariat PB to tow my Airstream...everything was good until I got this message. I checked all the Trailer turn signals and they both work fine when Im hooked up. Power to my Airstream's BT rear camera, trailer brakes, side marker lights and as mentioned the turn signal lamps. The truck recognized that the trailer was connected and did al the enabling/disabling of the different systems.

The message keeps coming up even after I acknowledge it by hitting OK. Sometimes it goes away sometime I have to hit the OK. Also took a picture of the plug on the F150 and the the 7-way from the Airstream. I am going to look up the 7 way plug diagram and see if there is something off...but everything works. Anybody have an idea?

I had the same with a trailer, but mine said LEFT message, Same message. Yet all lamps worked fine.

 

[notabot]

Same issues everyone is having on my '21 Lariat.

Using Flat-5 to 7-pin worked today in all conditions. Strange...

 

[azDcab21]

I ran into the same issue my last trip. I had run over 1200mi without an issue. The main change was mid-tow, I thought I had forgot to turn off the electric heater, so instead of opening everything up I simply flipped my battery cut off switch in the rig. All seemed fine the next 50 miles or so. Then on the next off ramp, I signal and get the fault messaging (right turn lamp fault) and the fast blinker inside. Pull over to investigate. Although it was a speed blinker inside outside was fine all the plugs were in and looked great. Got it home. Today, I hook up to put it in storage but, this time turned the cut off back on, (which I normally always do) and all is well.

 

[RexTX]

THAT sounds like a ground issue. Has anyone tried connecting a perfect ground wire from trailer to truck? And check the grounds at the lights?

 

[Fomoco65]

I just traded my 18 F150 super crew in last week for the 21 version. I’m having an odd trailer light issue as well, wondering if anyone had any insight.
I hauled my galvanized dump trailer to a job site Monday morning with my 18. No issues as usual.This trailer isn’t quite a year old yet, and I’ve never had a problem. Traded the truck Monday afternoon, and when I hooked onto the dump trailer with the 21 Tuesday morning, checked the lights and all was good. Headed down the road and got the “trailer light module fault” warning. I pulled over, checked the lights again, everything seemed to work so I continued on. The warning continued to pop up every 20 seconds or so. I’d hit ok, clear it and it would come back. Luckily I didn’t have far to go. When I got back to the site, I got one of my guys to help me check. When I hooked up and checked the lights, all was good. As soon as I pull the truck in gear, I lose both signal lights and brake lights. Back in park, they work. Also, as soon as I shift out of park, the trailer marker lights come on. This is my sixth F150 since 07, and I’ve never had one do that before. And yes, since it’s a new truck I took it back to the dealer, but so far they’ve got nothing. The “tech network” says it must be trailer related, and that would make sense because my 13 year old enclosed cargo trailer works no problem. It just doesn’t add up to me because my 18 had no problems, and I took both the truck and trailer to the dealer and they tried a 19 they had there and it worked fine. But another 21 they had on the lot did the same thing as mine. It doesn’t make many sense to me at all. Any thoughts? Side note, one of my guys hooked his 18 GMC up last week just to see, and the trailer lights worked fine.

I cut my trailer plug off and put a new one on,working perfect.

 

[Steyreo]

I’ll add to the list of people with this problem. For me, it started when I switched to LED taillight bulbs in our vintage trailer. As somebody said above, we only get the error when the headlights are on. I tried installing resistors but that didn’t seem to do anything.

We also get the “trailer disconnected” error that many others have experienced. The pattern with that is that it seems to happen after stopping to get gas. I thought that it might be related to arming the alarm but it happened once after I hadn’t done that. It never happens to us suddenly in the middle of a drive. I know, different thread, but just thought I’d mention that here too in case it was related.

If this is just about the truck not liking LED bulbs, that’s kind of ridiculous. In 2021(2), let’s just expect that people will be using LED bulbs.

 

[Fomoco65]

Hey guys - just setting up my new Lariat PB to tow my Airstream...everything was good until I got this message. I checked all the Trailer turn signals and they both work fine when Im hooked up. Power to my Airstream's BT rear camera, trailer brakes, side marker lights and as mentioned the turn signal lamps. The truck recognized that the trailer was connected and did al the enabling/disabling of the different systems.

The message keeps coming up even after I acknowledge it by hitting OK. Sometimes it goes away sometime I have to hit the OK. Also took a picture of the plug on the F150 and the the 7-way from the Airstream. I am going to look up the 7 way plug diagram and see if there is something off...but everything works. Anybody have an idea?

Had same issue ,cut trailer plug off and put a new one on .No faults!