If I read correctly this code occurs at speed. You need to check your encoder as noted above. Also check the shaft on top of the brake that the encoder mounts to - make sure that it is tight. More likely though, you either have a mechanical brake issue, the brake is worn out, or your brake cylinder is leaking. This code with travel more signifies that you have a stopping problem than an encoder problem.
I would recoment plugging to stop vs taking your foot off of the deadman pedal.