There's a kit for the 700R4 that uses Hydraulic pressure alone to lock the Torque Converter Clutch but, unless this is installed or you correct the TCC wiring it wont lockup on it's own without an electrical connection.
TransGo Part# 700-LU >>
http://www.transgo.com/valve_bushing.php
I'd just swap the Harness from your original Trans to the new one.