Torque Converter Clutch Solinoid

I just swapped an engine for a 2001 Isuzu Rodeo. The wiring harness that comes from the engine to the transmission has given me a problem because I cannot locate the home of one wire. It is a four pronged male connector. I assume it is the reason for my trans. warning light. The vehicle will not shift. It acts like it is in N no matter where you move the shift lever. Any ideas as to where I need to be looking for this electrical connection would be greatly appreciated. This is a two wheel drive automatic model.