How to Test Older Featherlight Trailer Wiring to Confirm Correct 7-Way Installation

Question:

In the answer for this it was said blues would match up but farther down then said red to blue on trailer. Do both red and blue from trailer go into blue?

asked by: Rainie

Expert Reply:

A wire's color alone is not a reliable way to know the function carried on it. Although there are commonly used color-to-function assignments, such as a blue wire being used for a trailer's brake circuit, there is never a guarantee that your specific trailer follows those assignments. The older a trailer is the more likely that it has needed some re-wiring along the way so it is better to test each wire to confirm its function.

Installing a new trailer 7-way and junction box like # HS381-9000 is best done by following the wiring configuration shown in the linked photo and article. You can confirm what each wire on the trailer does by applying 12V power from a well-charged battery to the ground and to each wire/circuit (one at a time) to see what function activates on the trailer. Then just match up the function to the pin assignment shown in the photo.

expert reply by: Adam R