Installing 7-Way Junction Box to Avoid Use of Wiring Adapters

Question:

I have a 7 pin connector installed on a 2011 Toyota Highlander and use it to connect to a camper. All lights/brakes work fine when 7 pin vehicle connection is made to 7 pin camper trailer. However, when I try to use a 4 pin adapter for a utility trailer, I get no lights. I back tested the utility trailer lights using a battery charger and all worked fine. But something about using a 7 to 4 pin adapter is not working right. Another tidbit: when I try to use a tester on the vehicle end to light up a connections, nothing lights up. Pretty certain all are grounded appropriately. Do you have any suggestions on how I can troubleshoot and resolve this? Thank you.

asked by: Dan

Expert Reply:

Since your 7-way-equipped trailer's lights and brake's function when connected to the 7-way on your Highlander you ought to be able to detect those same signals on the vehicle's 7-way socket using a circuit tester like # PTW2993 when no trailer is connected. Those signals should be present either way. Make sure your tester is properly grounded when you test the circuits.

Given the choice of using or not using any type of adapter, I always suggest avoiding them whenever possible. Extra connections tend to mean more chance for connectivity issues.

I suggest you install on the utility trailer a 7-way/junction box # HS381-9000 using ring terminals # 44-5310A. Just connect the existing 4-pole wiring to the appropriate terminals inside the junction box and then plug in the pre-wired 7-way to your Highlander. The junction box not only lets you avoid the adapter, but it will also simplify any future wiring repairs needed and make it easy to add lights to the trailer should you wish to do so.

expert reply by: Adam R