Is any option to bypass that switch
If you haven't figured it out yet you might want to look down and buy all the hydraulic connections on top right of the transmission there's two connectors for the switches they get dirty and cause bad connection.
I found the switch and it seems to work for the dash light. How do you test the shift side?
Check your parking brake switches,there are two,one is for the dash bulb the other is for the start circuit and also provides the ground circuit for the fwd/rev Solenoids.either there is a wire off of the switch or the switch itself is bad,switches are located at the top of the park brake foot pedal....