Just to add, You can check resistance across A & B terminals, then C & D terminals, 40--80 ohms. If not as specified replace iac.
Check resistance between B & C, then A & D terminals, infinite resistance, If not replace iac.
It sounds to me like the iac is working correctly. With engine idling, block off the mouth of throttle-body, does it kill the engine?
Monday, August 27th, 2018 AT 10:47 AM