02 sport 4wd engaging problem

[Kams979]

having the issue with the 4wd not engaging properly. Started off with the normal acting up scenario having it not engaging right away or going through the motions of R-N-D to get it to set. Now im having the problem where it will only engage if I press the 4WD button "and the indicator starts to flash" I turn it off, then back on again and will be engaged but with the center diff locked. Once it is engaged I push the center diff button it turns off as normal. any ideas on what it could be? I pulled both sensors and cleaned them with some electronic cleaner and worked the switch but still having issue. thanks