That idle air control unit basically bypasses air around the throttle body butterfly in conjuction with signals from the computer, temp sensors, etc. until the engine warms up. It also maintains idle after that. Here is some basic good info on the toyota systems.

Autoshop101

Last edited by garym; 07/05/07 03:39 PM.
1997 T-100 4X4 Xcab,Warn Hubs
02 Camry LE
2008 Yaris