ECM Code EO30: Idle Speed Control Circuit Problem: Action:

ECM turns on SERVICE ENGINE SOON light. The ECM controls engine idle by increasing or decreasing throttle opening with Idle Speed Control (ISC) motor. The ISC controls idle speed any time throttle switch is closed. Code EO30 detects engine RPM out of limits.

Test Number 1)  This checks for proper throttle switch, power steering switch and park/neutral switch operation. The ECM must receive accurate switch status information to control idle.

Test Number 2)  This checks for proper ISC motor operation.

Test Number 3)  Many engine fuel and emissions system faults may cause unstable idle. If base engine idle is not steady, ISC may not be able to control idle to within 152 RPM of desired idle.