Transmission 1-2 shifts hard

[GablerEnt]

06 3500 dually w/48RE:
Recently started to shift firmly from 1 to 2 and wouldn't accomplish this shift unless truck was traveling above 20 mph, even under light throttle.
checked for trouble codes and discovered P0477, P0573 and P1753.
Had this problem about a year ago and a repair shop simply cleared the codes and the transmission performed normally until now.
How can I clear the codes myself?

 

[Ozymandias]

change the rear speed sensor at the transmission. cheap part but very important.

 

[GablerEnt]

Thanks, I'll try that....