Speedometer works when driven but then stops working

Recently bought from private owner; Cam sensor code noted, replaced, code cleared, no return; Left Rear Wheel Sensor Code; Brake - ABS - Air bag lights on dash lit; Speedometer works when cranked but then stops working within - 50 miles, sometimes does not work after initial cranking; cruise control does not work when speedometer is not working and sometimes works when speedometer is working, not consistent.

Replaced left rear sensor - appeared to solve problem other than lights on dash - with-in 50 miles problem surfaced again. Any thoughts on what to do next or something that should have been done first.