Troubleshooting 2007 Dodge Durango Tail Light Failure With Trailer Wiring Harness # 118390 Installed

Updated 06/16/2011 | Published 06/12/2011

Products Featured in This Question

7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket - Vehicle End

(2641)

$41.58

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(100)

$68.20

Question:

my trailer light modulator keeps burning up inside the modulator only the left turn and brake dont work this is my third one the first 2 i had from uhaul they installed the first one it didnt last long they replaced it bu i inastalled my self it didnt last the third i got from you the one that has the plugs to plug into the back lights and installed per directions now i have that problem with the left turn and break it works on the truck before the modulator but not after the modulator right turn and break works and all tail lights and running lights work weird i dont undrstand why this keeps happening maybe you could help thank you

asked by: Charles F

Expert Reply:

It sounds like there is a short circuit back feeding into the converter box of the trailer wiring harness # 118390. This would be an issue on the trailer side. You will want to make sure that the trailer connector is clean and corrosion free. Then move on to checking the grounds on the trailer. Trailer lights usually ground through the mounting studs. The main ground from the connector should be attached to the trailer frame. All grounds should be attached to clean and corrosion free bare metal surfaces.

You will also want to look for any loose connections, pinched wires, or any wiring with cracked or worn insulation that would allow the copper conductor to come into contact with the trailer frame and short out.

Once you are positive the trailer wiring is good, we can look at the vehicle. The # 118390 harness has a powered converter that requires a direct connection to the vehicle battery. No other 12 volt source should be used. Be sure to disconnect the negative battery terminal as stated in the instructions, linked for reference. I have also included a link to a video showing installation on a 2007 Durango.

expert reply by: Michael H