Troubleshooting Constant Power on Drivers Side Tail Light of Trailer Connector

Published 01/07/2019

Products Featured in This Question

Curt 7-Way to RV Socket LED Circuit Tester - Vehicle End

(174)

$19.90

Hopkins Endurance Multi-Tow 7-Way RV and 4-Way Flat Trailer Connector - Vehicle End

(64)

$28.07

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

(2644)

$44.18

Hook Probe Circuit Tester

(62)

$13.94

Question:

I have constant power to the left side tail light trailer wire harness. The harness in the truck when adapter is removed still shows power from Main harness. I disconnected 12 volt power at fuse panel and still have constant power to left tail light. Also when I turn the right blinker on in a trailer lights both tail lights blink. Left blinker blinks as normal. All brand new plugs Factory plug-in wiring all Newgrounds.

asked by: Brian P

Expert Reply:

It sounds like you have a crossed wire after the fuse panel. Sometimes this happens inside the trailer connector, so I recommend removing your trailer connector and using a circuit tester like # PTW2993 to test each of the wire functions at the US Car Connection locations like you see on this harness # 20147. If this connection works correctly then you will want to replace the 7-way connector on your vehicle because it has an internal issue. If this is the case, I recommend the Hopkins Endurance Multi-Tow 7-Way RV and 4-Way Flat # HM40950 or # HM40975.

If the harness is having the same issue on the US Car Connection then you will need to trace your wiring probing every few feet to determine the location of the short. If you can't find it, I recommend taking it to a mechanic to assist as the wiring does get complicated, but you should be able to trace it.

expert reply by: Jason S