What are the Functions of the Relays Included in the Nissan Trailer Wiring Harness # C56225

Question:

I just installed a trailer wiring harness on my 2011 Nissan Frontier. I purchased the kit from etrailer. The installation was easy and the kit is excellent quality. I just have to know what function the 3 relays provide? I have installed many trailer lighting kids in the past and none have ever included relays. Can you provide a brief explanation?

asked by: Bob L

Helpful Expert Reply:

Absolutely, the three relays attach to the jumper harness that installs behind the passenger side kick panel. The large brown relay provides 12v power to the trailer connector at the rear bumper. It looks like you purchased the 4-pole harness, # C56225, so this relay is not of much use to you right now. If you ever wanted to upgrade to a 7-way trailer connector, then you could add the Replacement Wiring Harness, # 118267. This would use the brown 12v power relay.

One of the small blue relays is for the running light circuit for the trailer wiring harness. Without this relay, the running lights would not work on your trailer. The other blue relay is included with all harnesses, but it is only required for manual transmission models. If you have an automatic transmission, then you can still install the relay, but it will have no active function. The blue relays are the same size and rating, so they can be used on either connector of the jumper harness. They aren't specific.

I have attached an installation video for the 7-way wiring harness for you to check out if you ever consider upgrading your trailer wiring.

expert reply by: John H