Troubleshooting Trailer Lights with Nissan Frontier Using 7-Way to 6-Way Adapter

Question:

I have a factory towing system on my nissan Frontier. I had to place a male plug in but the other end of the pigtail is a female to the trailor. I thought I went by the wiring instructions but.. When I turn my right blinkers on, my two trailor lights on the left blinks and the inside light on the right side blinks. and the outside stays on. Vehicle head lights are on. When I turn on the left blinkers on, the blinker out side works but the inside left and right lights stays off but the outside right stays on. What have I done wrong?

asked by: David

Expert Reply:

There are two likely possibilities for the lighting issue you're having. It sounds like you may be using an adapter to match up your Frontier's factory 7-way trailer socket to the 6-way plug on your trailer. It is possible that the adapter you're using is causing the issue with your lights since 6-ways can be wired in two different ways. It may also be that there is a bad ground connection either on the vehicle's harness or on the trailer's harness. A weak ground can cause all sorts of odd behavior from the trailer lights.

First, I suggest you check that both the vehicle's and the trailer's main wiring grounds are secured to a clean bare metal surface for good metal-to-metal contact. You can clean or sand those grounding points to ensure a solid connection. Also inspect the connectors themselves, inside and out, for any signs of corrosion that could be causing the problem.

You may also want to double-check your wiring. The linked article includes photos of the different types of trailer connectors and how they can be configured by pin and function. It is usually best to avoid use of adapters since these introduce additional contacts and so more chances for a problem.

You may be best served by wiring in a new 7-way plug on your trailer, such as # H20046, using a junction box like # 38656. This way your trailer will plug right into your Frontier without all the extra connections and complications of an adapter. You'll need 10 of ring terminal # DW05702-1 and 4 of terminal # 44-5310A to make all 14 wiring connections at the junction box.

It is always best to use a tester like #
on the truck wiring to confirm what function each wire carries, and on the trailer, you can use a spare 12V battery (or the one in the truck) to test each circuit on the trailer to confirm what signals each wire carries. Then it's a straightforward process of joining the 7-way plug's wiring to the trailer's wiring inside the junction box, matching them by function.