We replaced both parts, the harness side where it plugs into, as well as the key side on the outer column part. It came complete. The starter relay would be cheaper, so I would go with that first if you already tested it. I would test the wiring on the ignition to see if you are getting power going through it, also check to see if your relay is working too. I have seen it once on another friend of mine's truck, where the relay had power going to it, but was not clicking over and sending the power out. I would test them both before you spend money just replacing random parts, but they are pretty easy to test.
