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Home >> Chevrolet >> 2006 >> Impala LTZ >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 3.9L - DTC P0010 To DTC P0420 >> DTC P0340, P0341 or P0342 >> Circuit/System Testing
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Circuit/System Testing

  1. With the ignition OFF, inspect the engine wiring harnesses carrying the CMP sensor circuits for the following conditions:
    • Close routing of secondary ignition wires
    • Close routing of aftermarket electrical equipment
    • Close to solenoids, motors, and relays
    • Correct any wire harness routing or component placement conditions, if it is determined to be a possible source of electrical interference.
  2. Disconnect the 16-way engine harness to fuel injector harness connector.
  3. With the ignition ON and the engine OFF, measure for 4.8-5.2 volts at the ECM side of the connector between the 5-volt reference circuit of the CMP sensor and a good ground.
    • If the voltage is less than 4.8 volts, test for an open in the 5-volt reference circuit between the ECM and the 16 way connector, or a faulty ECM.
  4. With the ignition ON and the engine OFF, measure for 4.8-5.2 volts at the ECM side of the connector between the CMP sensor signal circuit and a good ground.
    • If the voltage is less than 4.8 volts, test for an open or a short to ground in the CMP sensor signal circuit between the ECM and the 16-way connector, or a faulty ECM.
    • If the voltage is more than 5.2 volts, test for a short to voltage in the CMP sensor signal circuit between the ECM and the 16-way connector, or a faulty ECM.
  5. With the ignition ON and the engine OFF, measure for 1-3 mA, at the ECM side of the connector between the CMP sensor signal circuit and a good ground.
    • If the amperage is more than 3 mA, test the CMP sensor signal circuit for a short to the 5-volt reference circuit between the ECM and the 16-way connector, or a faulty ECM.
  6. Connect a fused jumper wire to a good ground.
  7. With the ignition ON and the engine OFF, observe the CMP Sensor parameter on the scan tool.
  8. Touch the jumper wire to the CMP sensor signal circuit repeatedly at the ECM side of the connector. The CMP Sensor parameter should display a value other than 0 RPM.
    • If the CMP Sensor parameter displays 0 RPM, replace the ECM.
  9. With the ignition ON and the engine OFF, measure for B+ at the ECM side of the connector between the low reference circuit of the CMP sensor and the battery positive post.
    • If the voltage measured between the low reference circuit and the battery positive post is not the same as voltage measured between a good ground and the battery positive post, test for an open/high resistance in the low reference circuit between the ECM and the 16-way connector, or a faulty ECM.
  10. With the ignition OFF, remove the power steering pump and inspect the wiring harness, from the 16-way connector to the CMP sensor, for any damage, opens, or shorts. Refer to Power Steering Pump Replacement (LS4) or Power Steering Pump Replacement (LZ4/LZE/LZ9) .
    • Repair any wiring or connector damage, if necessary.
  11. Inspect the CMP sensor for looseness. Remove the CMP sensor from the engine and inspect the sensor and the O-ring for damage.
    • Repair or replace the CMP sensor, if necessary.
  12. Reconnect the 16-way connector and the CMP sensor to the engine harness.
  13. Turn ON the ignition, with the engine OFF.
  14. While observing the CMP Sensor and CMP Active Counter parameters on the scan tool, pass a steel object by the tip of the sensor repeatedly. The CMP Active Counter parameter should increment and the CMP Sensor parameter should display a value other than 0 RPM.
    • If the parameters remain at 0, replace the CMP sensor.
  15. With the ignition OFF, drain the engine oil. Refer to Engine Oil and Oil Filter Replacement , and inspect the engine oil for debris.
    • If debris is found in the engine oil, inspect the internal engine components to determine the cause.
  16. With the ignition OFF, remove the camshaft from the engine, refer to Camshaft Removal and Camshaft and Bearings Cleaning and Inspection . Inspect the camshaft reluctor wheel for damage.
    • If the reluctor wheel is damaged, replace the camshaft.
  17. With the ignition OFF, remove the engine front cover, refer to Engine Front Cover Replacement and inspect the timing chain, tensioner, and sprockets for wear or damage. Refer to Timing Chain and Sprockets Cleaning and Inspection .
    • If any parts are worn or damaged, replace as necessary.
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