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Idle Air Control Valve (Spectrum Turbo)

  1. Warm engine to normal operating temperature. Record idle RPM in Neutral. Turn ignition off. Disconnect IAC valve. Start engine. Record idle RPM in Neutral. If RPM increases, go to next step. If RPM does NOT increase, go to step 3).
  2. Turn ignition off. Reconnect IAC valve. Start engine. Record engine RPM. If RPM returned to specification recorded in step 1), IAC valve is functioning properly. If RPM did NOT return to specification recorded in step 1), go to next step.
  3. Turn ignition on with engine off. Ground diagnostic test terminal. Connect a test light between each IAC valve harness terminal and ground. If test light illuminates on all terminals, repair faulty IAC valve terminal connectors or replace faulty IAC valve. If test light does not illuminate on one or more terminals, check circuit that did not light for an open or short.
  4. If circuits that did not light are okay, check resistance across IAC terminals. Connect an ohmmeter between IAC terminals "A" and "B", then "C" and "D". Ohmmeter should read more than 20 ohms.
  5. If ohmmeter read more than 20 ohms, repair faulty ECM connector or replace faulty ECM. If ohmmeter reads less than 20 ohms, replace faulty IAC valve and replace ECM.
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