what does the throttle body coolant bypass do what purpose does it serve thanks

 

This heater keeps your throttle from freezing in the wide open position by circulating hot fluids through it, thus heating it up and transferring the heat to your throttle-body. But this is only a concern in the colder regions.

 

There's a very good discussion about this topic here:
http://k-series.com/forums/viewtopic.php?t=1535