4x4 knob randomly not working

[dustin h]

I have a 2016 ram 2500 6.7 liter cummins, the 4x4 switch on the dash stopped working. I noticed for a few weeks that the lights in the switch module were off then would randomly come back on. When lights were off you could not shift into 4x4, its like you were doing nothing when you would turn the knob. No lights or codes on dash no attempting to shift into 4wd. Would work fine if knob lights were on. Now they are off for good and i cannot shift into 4wd. All wires look good to it and to the transfer case. Are these knob style shifters a common problem? I see there is an old thread on here saying thag pedal camanders were the issue but i do not have one of those. Im thinking switch was just slowely going out... not sure. Anyone know what the voltage hoing to the knob should be?