If it has 2 Switches, They are Easy to check, One is normally open and the other is normally closed, When you Start the engine,. they change over.
Use 2 test lamps clipped to Battery positive, and connect the other end to each oil switch, One should be on and one should be off, Start the engine and one should go out and the other should come on, If They both do the same, one of the switches is wrong. if either don't change then they are faulty.