The 700 only needs 12v and ground to lock up. I don't like using a manual lock up switch. The main reason, if you forget to turn the switch off, the transmission will stay locked up even when you are trying to come to a stop. Could be a dangerous situation. I have mine set up the lock up when the trans shifts into 4th gear, via a pressure switch sensing 4th gear hydraulic pressure. When the pressure switch senses pressure, it closes and ports 12v to ground locking the convertor. I will say I do have the option of manually locking the converter, but I haven't hooked that circuit up yet, and probably won't.