E030

TEST CONDITIONS
1. Codes EO21, EO22, EO24, EO26, and EO27 not set;
2. Throttle switch closed;
3. Vehicle speed = 0 MPH;
4. Battery voltage equal to or greater than 11 volts;
5. Desired idle RPM 152 different then actual RPM;
6. Engine has been running for more than 7 seconds;
7. Engine not receiving a power steering load;
8. ECM is not commanding an idle speed anticipate.

FAILURE CONDITIONS
TPS less than or equal to 14 degrees and ISC is extending for 15 seconds or TPS equal to or greater than 2 degrees and ISC is retracting for 15 seconds.

ACTION TAKEN
1. ECM turns on the "Engine Control System Fault" telltale and keeps it on for the entire ignition cycle;
2. ECM commands BCM to display "Service Soon" message on Driver Information Center (DIC).

DESCRIPTION
The ECM controls idle RPM by increasing or decreasing the throttle opening using the Idle Speed Control (ISC) motor. The ISC motor will control engine RPM any time the Throttle Switch is closed (foot off the accelerator). Code EO30 sets because the actual RPM never reaches desired RPM signifying a slow or failed ISC motor.

Notes on Fault Tree
1. Checking for misadjusted TPS.
2. Checking for proper throttle switch, brake switch, and park/neutral switch operation. The ECM must receive accurate switch status information in order to control idle speed.
3. Checking proper ISC motor operation.
4. Many engine fuel and emissions system faults may cause unstable idle. If the base engine idle is not steady, the ISC may not be able to control idle to within 150 RPM of commanded idle speed.
5. Out of adjusted minimum air rate, ISC, or TPS can cause ISC not to control idle and code EO30 to set falsely. Check adjustment per instructions.
6. Checking ISC motor circuits for proper operation:


NOTE: Throttle switch input to ECM must be jumpered in order to allow ISC to cycle.


Notes on Intermittents
Display ECM Data ED01, manipulate TPS wiring and connectors, watch for TPS value to jump or skip. Observe throttle switch status (low fan) while manipulating affected wiring. If the status light flashes, check for intermittent open circuit on CKT 427. Verify that minimum air RPM, ISC and TPS are set to specification. If idle is unstable, see Symptom chart "Rough, Unstable, Incorrect Idle, Stalling". Testing and Inspection