Note on Intermittents

If an intermittent Code 30 is being set before cold starts, the ISC motor may not be adjusted properly. To simulate a cold start, turn the ignition on, enter diagnostics and then momentarily disconnect the coolant temp sensor connector. Being in diagnostics will keep Code 15 from setting and the ECM will see a coolant temperature reading of -40° to -35°C. If the ISC motor ratchets at this point, the minimum air rate, TPS and ISC motor adjustments should be checked.

If an intermittent Code 30 is being set after start-up, manipulate related wiring while in output cycling (code .9.6). If the failure is induced, the ISC motor will stop cycling in one or both directions. This will help to isolate the location of the malfunction.

A Code 30 may be stored along with a Code 19 Shorted Fuel Pump Circuit. If Code 30 no longer appears after Code 19 has been corrected, do not investigate any further. The voltage on the fuel pump feedback circuit made the ECM improperly test Code 30.