Don't know which switch you are talking about. The 700R4 and the 200R4 both use a pressure switch that measures the hydraulic line pressure that feeds the OD piston to engage the clutch that limits the slip in the torque converter. You need to install a second wire to your brake light switch to disengage the lock up feature whenever you try and stop the car.
The valve body is a just collection of pressure switches that controls the transmission based upon gear selector position, governor weights and springs as well as check balls (one way valves) to control the transmissions operation instead of a computer. So I am not sure which pressure valve you are talking about. I'm no transmission guy I have to get the Service manual out to rebuild one, though I have done it several times (they are not that complex to repair just requiring three special tools that cost about the same as you would pay someone else in labor to fix yours).