Welcome to iRV2.
I have to ask , what chassis and engine your coach has .
When you say " Transmission neutral switch does not come on ." Does this mean you have a push button shifter and the display, doesn't display " N ".
Yes there is a starter relay , that takes a signal from the ignition switch , and the neutral safety switch , before supplying voltage to the solenoid on the starter .
Location of the starter relay depends on what chassis you have.