931 Brake Light problem

[Jerome Ryals]

Done a lot of searching here and on the 924board regarding my '80 931 brake light problem. Almost got rear-ended twice on the way home a couple days ago, got home and checked-no brake lights as suspected. Everything else works fine, did the usual - checked fuses, clean all grounds, new bulbs, cleaned bulb housings, etc. but still no brake lights. I figure it must be the switch(s) even though I have not checked them yet (there are two pressure switches on the master cylinder of this car). I am planning to change over to the plunger style used later on but my big question is 'why are there three wires going to each of the pressure switches mounted on the master cylinder'. Thanks for any answers, Jerome.