How Do Trailers Maintain Ground Connection from Tow Vehicle

Updated 06/29/2016 | Published 06/28/2016

Question:

Do trailers need to be grounded to the hitch with a 7 point hardware

asked by: Tom

Expert Reply:

A trailer will use the vehicle's ground on the 7-way (or 4-pole), usually carried on the white wire, for its lights, brakes, etc. As you look at the vehicle 7-way socket (please see the linked photo) the ground is usually carried on the pin at the 7-o-clock position. It should not be necessary to make any ground connection to the hitch itself. In actual use the coupler/hitch ball connection does provide a degree of grounding for the trailer, but this will not be enough for all of the lights, brakes, etc.

If you are having any trouble with some light functions not working, try cleaning off any discoloration or corrosion on the metal pins, especially the pin for the ground, on both vehicle and trailer connectors.

expert reply by: Adam R