2004 Chevy Blazer ABS Light after ball joint repair

So I just spent Saturday morning replacing all 4 ball joints on my 04' chevy blazer ZR2. A buddy and I took on the project in an effort to save a lot of money at the local shop. Unfotunately since the was our first go around with these, I may have shot my self in the foot here. We got everything in great but when I went to take a test drive the ABS light is on. I checked the ABS wiring into the hub and there is no visible damage anywhere. Although I ignorantly forgot to unplug them while pulling the hub aside for the ball joint replacment and I know its something we did, maybe too much pressure or something on the wire. How sensitive are the wheel speed sensors? I can get a new one for $36 bucks, but I don't know which one to change. And when I change it do I need to take the whole hub and everything off or can I just get at it from the back? It looks like all I need is an allen key. Basically should I just try to swap the sensor out, or am I better off letting the dealer do it and not messing up anything else? Oh yeah and will the ABS light clear when the part is replaced or will it need some kind of reset?