Odd IAC Retract Issue
 

Vehicle is a 1987 Cherokee with the 4.0 engine.

The problem that I am having is that the Idle Air Control valve/Idle Stepper Motor is not retracting when the engine is turned off with the key. The IAC/ISM only retracts if the engine fails to start during cranking or dies while running. This is causing a very rough idle at start up. Sometimes the engine sputters and dies after start up.

I checked the sensor ground resistance and it was a whopping 130 Ohms! I cleaned grounds, cleaned the C101 connector, and soldered the spliced grounds in the wire harness together. Now the sensor ground resistance is around .8 ohms.

This is the second new IAC and the problem also happens with the original IAC. The power latch relay has been both replaced with new relays and swapped with known working relays.

What could cause the IAC to only retract when the engine dies or fails to start and not when the engine is turned off with the key?

Great job so far!!

Because the ECU retracts the IAC?