Brake light switch

[car-nut]

Hello all,
Does anyone know how to test the brake pedal switch? It has four prongs; I know a a pair of them should be open circuit (infinite resistance), until the switch is pressed; but, what about the other two prongs? What should be the resistance across those?
Any help would be appreciated.

BTW, when I looked at the wiring diagram, it shows three wires for the switch (go figures?!).
Cheers,
Zackman

[shyamvenky]

This might be of help.

ABS/PSM problem cured