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Home >> Chevrolet >> 2006 >> Impala LTZ >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 3.9L - DTC P0442 To DTC P2A01 >> DTC P1516, P2101, P2119, or P2176 >> Circuit/System Testing
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Circuit/System Testing

  1. Inspect the throttle body for the following conditions:
    • A throttle blade that is NOT in the rest position
    • A throttle valve that is binding open or closed
    • A throttle valve that is free to move open or closed WITHOUT spring pressure
  2. With the ignition ON, and the throttle body disconnected, measure for voltage between the TAC motor control 1 and 2 circuits and a good ground. The voltage should be 0 volts.
    • If voltage is more than 0 volts, test the affected motor control circuit for a short to voltage or a faulty ECM.
  3. With the ignition ON, and the throttle body disconnected, probe the TAC motor control 1 and 2 circuits with a test lamp connected to B+. The test lamp should not illuminate.
    • If test lamp illuminates, test the affected motor control circuit for a short to ground.
  4. Connect the throttle body.
  5. With the ignition ON and the engine OFF, clear the DTCs with the scan tool.
  6. Turn OFF the ignition for 60 seconds, and verify the ECM has powered down by observing No Comm. on the DTC Information menu of the scan tool.
  7. Disconnect the throttle body.
  8. Connect a test lamp between the TAC motor control 1 circuit and a good ground.
  9. Observe the test lamp while turning ON the ignition. The test lamp should illuminate for approximately 0.5 second.
    • If the test lamp does not illuminate, test the TAC motor control 1 circuit for an open, high resistance, or for a faulty ECM.
  10. Remove the test lamp and connect the throttle body.
  11. With the ignition ON and the engine OFF, clear the DTCs with the scan tool.
  12. Turn OFF the ignition for 60 seconds and verify the ECM has powered down by observing No Comm. on the DTC Information menu of the scan tool.
  13. Disconnect the throttle body.
  14. Connect the test lamp between the TAC motor control 2 circuit and a good ground.
  15. Observe the test lamp while turning ON the ignition. The test lamp should illuminate for approximately 0.5 second.
    • If the test lamp does not illuminate, test the TAC motor control 2 circuit for an open, high resistance, or for a faulty ECM.
  16. If all circuits test normal, replace the throttle body.
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