service brake system

Myself and a few other people have had problems after recalibrating the speedometer. Sometimes the speedometer will start to act lazy and start bouncing and then trigger the ABS and Parking Brake light. Service Brake System will show up on the Display.
I had swapped Gears and a few others had changed tire sizes.
Here's a link to a thread that was brought up. I've yet to find any resolve on the issue in any searches on the net.
http://www.performancetrucks.net/for...d.php?t=434702
All sensors are fine and I've checked my speedometer with my GPS and it's accurate all the way up the odometer.
The problem only happened after recalibrating.
Video:
http://s175.photobucket.com/albums/w...rvicebrake.flv

as of now im having the same problems. i check my brakes and they seem fine.