Troubleshooting Turn Signals Coming On When Pressing Brake Pedal After Converting to 7-Way

Question:

I recently added backup lights to my utility trailer and converted the previous 4-pin flat to a 7-blade round connector. All lights tested good when 12v power was applied directly into the new 7-blade connector, BUT when I plugged the new 7-blade into my sons 2023 F150, and the brakes were applied, both the brakes and the turn signals came on at the same time. I tried this again on my daughters 2023 Jeep and the same thing happened. What did I do wrong? Do I need to add a white ground wire to my trailer chassis plus run a ground to the 7-blade connection? Or do I maybe need just a ground to the chassis? Im SOOOOO confused. :-

asked by: John

Expert Reply:

To start I have attached a help article of ours near the bottom of the page which covers 7-way wiring. On your utility trailer the turn signals and brake lights would have the same circuit from the vehicle. If you installed some different tail lights which have separate turn signals then you would need to add a Converter # C56196 to separate the signals for the lights. This converter is only designed for use with incandescent tail lights so if you have LED tail lights you will need to add a Resistor # P230004A to each circuit.

expert reply by: Bud M

John

4/11/2024

Thanks Bud for the quick response. Sorry, I should have been more clear in my explanation of the problem I'm experiencing. My trailer wiring and lights worked perfectly, including the added backup lights. The problem was experienced with the two vehicles, which messed up when I plugged the newly wired 7-blade round into them and applied the vehicle brakes and/or turn signals. Both vehicles (new F-150 and a new Jeep - both with all kinds of drive/parking assist) did the same thing - when their brakes /turn signals were applied, the vehicle brake lights and the vehicle turn signals both came on and stayed on as long as the brakes/turn signals were engaged. BTW - I used the etrailer.com wiring diagram to wire the 7-blade...ground, left turn/brakes, right turn/brakes, running lights, backup. THANKS again - worked like a champ! I found some articles on line that said folks were experiencing difficulty with the more modern 7-way traditional connections which were reacting weird when trailer LED lighting systems were moved from 4 pin flat to 7 blade round. I was hoping that you guys had some insights into that., or more specifically, the dual brake/turn signal issue. I'm having. Thanks a bunch. john

Bud M.

4/16/2024

@John I'm sorry John, this is a new issue I have never heard of on either the F-150 or Jeep. I do know there are some European vehicles which require a Adapter # 20142 when connecting to a trailer with LED lights. This device tricks the computer into not seeing an issue with the much lower power draw of LED's that makes it think there is a bulb out on the trailer.