Shift indicator not indicating position

Chevy 2002 2wd extended cab, 200K+ miles, auto,
have replaced fuel pump in last couple of months.

Has had intermittent issue where the indicator would show in N but actually be in D. Now, only P illuminates and will not start. When the brake pedal is depressed and shifter is moved to any other position it doesn't show. Fails to turn over.
It leads me to think there is a swith or cable or connection that isn't making.
Suggestions?