May be a Temp switch, the Round switches that screw into Valvebody are Pressure switches. Temp switch prevents TC Lockup at low temps and and some force Lockup at very high temps.
There are many different wiring Combos. You should be able to just make it match the wiring from your old Trans. May have to remove switches & plug a few ports. 1/8" NPT plugs.
Lots of good 700R4 wiring Info here >> http://www.rowand.net/Shop/Tech/LockupTCCWiring.htm