Code 35: IAC Idle Speed Error: Notes

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This code is intended to detect intake vacuum leaks. The following conditions must be met to set a Code 35:

Engine speed at least 175 RPM more or less than specification.
TPS signal voltage indicates throttle position less than one percent.
VSS indicates vehicle speed is less than 3 MPH.
Above conditions are met for at least 5 seconds and IAC counts are less than 10.

NOTE: Test numbers refer to test numbers on diagnostic chart.

The IAC tester extends or retracts the IAC valve. Valve movement is verified by an RPM change. If engine speed doesn't change, valve can be retested after removal from throttle body.
This step checks IAC movement quality. Between 700-1500 RPM, engine speed should change smoothly with each tester light flash in both extend and retract. If IAC valve is retracted beyond control range (about 1500 RPM), it may take many flashes in the extend position before engine speed begins to drop. This is normal on certain engines. Fully extending IAC may cause engine stall. This is normal.