You can get the following kit from your Nissan dealer to replace your Pathfinder's 4-pin trailer connector with a 7-pin connector that allows electronic brake control.
http://www.courtesyparts.com/receiver-h ... 7314_7631&
You will also need a trailer brake controller and an adapter cable to go from the controller to the Pathfinder's trailer brake wiring harness, located behind your dash.
I use the Tekonsha Prodigy brake controller and also got the Tekonsha cable to for Nissan vehicles. Both of these items are available at good prices from www.etrailer.com
Hope this helps.