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Home >> Chevrolet >> 2007 >> Optra5 LS, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 1.4L DOHC >> Diagnostic Information and Procedures >> DTC P2101, P2118, or P2119 >> Circuit/System Testing
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Circuit/System Testing

  1. Verify that the following conditions do not exist:
    • The throttle body is not damage or modified
    • Vacuum leaks
    • A restricted air intake system
    • Excessive deposits on the throttle plate or bore
    • The throttle shaft for binding
    • The throttle linkage or the throttle cable for binding
    • Incorrectly installed PCV valve or hose
    • A malfunctioning PCV valve
    • If you find any of the above conditions, repair as necessary.
  2. Ignition OFF, disconnect the harness connector of the ISC motor.
    3. IMPORTANT: The test lamp is used to load the circuit and may not illuminate.
  3. Connect a test lamp between the high control circuit of the ISC motor and the negative terminal of the battery.
  4. Ignition ON, test for less than 0.3 volt between the high control circuit of the ISC motor and the positive terminal of the battery.
    • If greater than 0.3 volt, test the high control circuit of the ISC motor for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.
    5. IMPORTANT: Use the AC volt scale on the DMM. The millivolt scale will produce an inaccurate reading.
  5. Engine running, test for 30-40 hertz on the AC scale between the high control circuit of the ISC motor and the negative terminal of the battery.
    • If frequency is not between 30-40 hertz, test the high control circuit of the ISC motor for a short to voltage. If the circuit/connections test normal, replace the ECM.
  6. Ignition OFF, connect a test lamp between the low control circuit of the ISC motor and the positive terminal of the battery.
    • If test lamp illuminates, test the low control circuit of the ISC motor for a short to ground. If the circuit/connections test normal, replace the ECM.
  7. Ignition ON, test for less than 0.3 volt between the low control circuit of the ISC motor and the negative terminal of the battery.
    • If greater than 0.3 volt, test the low control circuit of the ISC motor for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
  8. Ignition ON, connect a test lamp between the 5-volt reference circuit of the ISC motor and the negative terminal of the battery.
  9. Test for 4.8-5.2 volts between the 5-volt reference circuit of the ISC motor and the negative terminal of the battery.
    • If less than 4.8 volts, test the 5-volt reference circuit of the ISC motor for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.
  10. If all circuits/connections test normal, test or replace the ISC motor.
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