Should LED Trailer Lights be Mixed with Incandescent Trailer Lights

Updated 03/02/2025 | Published 05/23/2011

Question:

Is okay to have a mixture of incandescent and LED marker lights on a trailer and even on the same line? I have a broken incandescent fixture and if I want to switch to LED do I have to replace all of them at the same time?

asked by: Ken S

Expert Reply:

One main difference between LED lights and incandescents is the amount of power each one draws. I did a little research and found that if you were to have LEDs and incandescents on the same circuit, it would be too much power draw for the LEDs without using the proper resistors to compensate for the differences. It would be best to replace all the lights to one type or the other.

However, if one of your stop/turn lights was LED and the other was not, that should be fine (provided both were designed to work on a 12 volt system, 24 volts for some applications) because they are not on the same circuit. But running lights all share the same circuit so it would be best and easiest to keep them all the same type.

expert reply by: Michael H

George B.

3/1/2025

Howdy Michael, I have. 2024 Tesla Model Y. Apparently it puts out 16 volts to the trailer harness instead of the traditional 12 volts. I have 6 trailers and one is giving me issues. The problem child is my new Scamp trailer. With taillights and running lights on the system works until either the turn signal or brakes are applied, then the car icon turns red indicating the car fuse has blown. ( I can reset the fuse magically on the car computer screen) This causes the taillights and running lights to turn off. The trailer lights are LED. Do you think changing out the lights to incandescent will alleviate the problem? Or maybe replacing the taillights with a lesser number of diodes would work? I have had the car into Tesla three times and have been assured by them the car is functioning fine. ( I disagree however) Any help would be appreciated, thank you, George Balmer

Robin H.

3/2/2025

@GeorgeB to me it sounds like a lamp out sensor which would be triggered by the low power draw from the LED lights. I would try an adapter like the # 20142 (7-way to 7-way) or # C35FR (7-way to 4/5-way). These have resistors built into them so it won't trigger that sensor anymore.