Abs and emergency brake light come on after driving a few miles. Speedometer reading is also off. Have been told it's a bad wheel speed sensor. How can I confirm this, and find out which one

 

My 02 2500 had the same problem. My tire place scanned it and one wheel thought I was going 50-60 mph while the other was no reading. I waited until I had a bearing go out and replaced both front hubs. Didn't affect the drivability and I saw no change in my breaks. While the light was on. New hubs solved all of my problems but I couldn't justify new hubs to turn off a light.

 

3 channel systems have a vss signal that is sent to the ebcm via the ecm. if this signal is lost it will effect all systems mentioned.
Get the codes read for a starting point.