HU Replacement

You will need to attach the wiring harness adapter you get separately(thats made for whatever year ridge you have) to the wiring harness that comes with the head unit together.

DO NOT CUT THE FACTORY HARNESS PLUGS OFF AND ATTACH THE HARNESS THAT COMES WITH THE HEAD UNIT DIRECTLY TO THE VEHICLE HARNESS!!

https://www.installdr.com/TechDocs/999008.asp

^^^What he said^^^

The wiring harness that came with the radio will plug into the radio and have bare wires coming out the end. The wiring harness you buy from Metra or Schosche will have a plug that connects to your factory wiring plug. The bare wires on the Metra or Schosche wiring harness will connect to the harness that plugs into the radio. I like to use solder and heat shrink for my connections.

That's the simple connections. There are more advanced connections to get your factory sub working and/or steering wheel controls working.