Troubleshooting Running Lights Circuit on a Travel Trailer Tail Light Harness

Updated 03/18/2010 | Published 03/16/2010

Products Featured in This Question

Optronics Trailer Tail Light - Stop, Turn, Tail - Incandescent - Round - Red Lens

(2660)

$8.40

3-Wire Pigtail for Optronics Trailer Lights - 3-Prong PL-3 Plug - 10" Lead

(396)

$4.94

Right Angle 3-Wire Pigtail for Optronics Trailer Lights - 3-Prong PL-3 Plug - 10" Lead

(689)

$8.68

Optronics Trailer Tail Light - Stop, Turn, Tail - Round - Grey Flange - Red Lens

(2660)

$7.80

Optronics LED Trailer Tail Light - Stop, Turn, Tail - Submersible - 10 Diodes - Round - Red Lens

(2232)

$16.51

Question:

Hello. I have a flat standred wiring from my vehicle green, yellow, brown white. Im installing brake lights-stop& turn lights to my back travel trailer. My new lights have red & black.on back I can get my turn signals and stop to work but no running lights. I have ground to trailer. But I get no power from the brown. Is there is certain way to hook up the red & black into the flat standred wire? Theres power from the car side but somewhere theres no power to the back, there is not splice from connection to back. Thanks

asked by: Gunther

Expert Reply:

Since you have tested the 4-Way connector on your vehicle and it is working properly, it leads me to believe that the wiring of the lights is incorrect. You will want to make sure that the fuse for the running lights on the vehicle is not blown. It sounds to me like the lights you have only have two wires coming out of the back for wiring to the trailer connectors wiring. If this is the case then the red wire will connect to the yellow (left) and green (right) wires on the trailer lights. The brown (tail light) wires will connect to the black wires on the trailer lights. The lights will receive their ground connection through the light housing and mounting screws which will need to be secured to the trailer frame.

If your application does not provide a mounting location that secures the light housings to the trailer frame you will need lights that have separate ground wires so they can be grounded to the trailer frame. We have lights similar to the one you selected that have a separate ground wire for mounting to surfaces that are not connected to the trailer frame. I will list a couple below for you.

Sealed, 4 inch Round Trailer Stop, Turn and Tail Light, Flange Mount, 3-Function, item # ST47RB
Sealed, 4 inch Round LED Trailer Stop, Turn and Tail Light, Flange Mount, 3-Function, item # STL42RB

With either of these lights you will need either the Straight 3-Wire Pigtail for Sealed Trailer Stop, Turn and Tail Lights, item # A45PB, or the Right Angle 3-Wire Pigtail for Sealed Trailer Stop, Turn and Tail Lights, item # A47PB.

I attached an FAQ article on trailer wiring for you to check out also.