Well, i just had a 2015 2500HD towed in to me for P0722. This started off as a head scratcher as it came with a brand new VSS installed and a new TCM ordered and on its way. So I check, and rechecked then triple checked EVERYTHING and no go.... Then my GM SET training kicked in and i went down the "personal strategy based diagnostics" rabbit hole. So i fabricated a harness extension to the VSS harness, took a 9/16 bolt and took a cut off wheel and cut many slots in the head to fabricate a test tone ring/reluctor wheel. I then took the sensor out of the transfer case and plugged it into my harness extension. Then I took my slotted head bolt, put it in a drill, turned the key on to the run position and started the drill then put the sensor close to the rotating slots AND VOILA speedometer came alive. I determined that the factory hold down brace was not formed properly and actualy popped the sensor UP and away from the transfer case output shaft tone ring as it was being tightened thus causing an excessive air gap and not allowing any signal to be detected by the TCM. I reformed the hold down brace, bolted it back in, reassembled truck to factory and BIZAM! Everythng operating as intended! ALSO! BE WARNED! ONCE P0722 IS SET, THE SPEEDOMETER WILL BEGIN WORKING USING ABS DATA! You need to be watching TCM live data for Vehicle Speed! If you've got a P0722 and your speedometer works, its using ABS data not VSS data!