double a ron

I will clean that ground, lines are all good, and get a better scanner. Thanks guys.

Hello all, first post, searched but haven't found anything online or in this forum for my particular issue. Truck is new to me, 2006 Sierra Denali AWD. I had it out yesterday in some snow and ice for the first time, all 4 brakes are locking up and rear end wants to come around, ABS not even attempting to work, no sound, pedal feel, or modulation on any surface. However I have no ABS lights, no codes, and fuse is good. Fluid level is good, no obvious issues noted. Any thoughts? Attached a pic to show her off.....