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Home › Saturn › 2003 › Ion 1 Standard › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0327: Knock Sensor Circuit › Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
    2. NOTE: If an engine knock can be heard, repair the engine mechanical condition before proceeding with this test procedure. Diagnose engine mechanical problem. See appropriate article in ENGINES.
  2. Observe the Freeze Frame/Failure Records data for this DTC. Turn the ignition OFF for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Does the DTC fail this ignition cycle? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  3. Turn ignition switch to OFF position. Disconnect the Knock Sensor (KS) harness connector. Set the DVOM to the ohms scale. Measure the resistance from the KS signal circuit on the sensor side of the KS harness connector to a good ground using the DVOM. Measure the resistance from the KS low reference circuit on the sensor side of the KS harness connector to a good ground. Does the DVOM display OL for both circuits? If yes, go to next step. If no, go to step  8.
    4. NOTE: Do not route the DVOM leads near an ignition control device or an incorrect reading may result.
  4. Connect a DVOM between the signal circuit of the KS and the low reference circuit of the KS on the sensor side of the KS harness connector. Set the DVOM to the AC scale. Start engine. Idle the engine for 2 minutes with the ECT above 180°F (82°C). Observe the DVOM while accelerating the engine from idle to 3000 RPM. Is the voltage below the 20 mV at idle and above 80 mV at 3000 RPM? If yes, go to next step. If no, go to step  8.
  5. Turn ignition switch to RUN position, engine OFF. Set the DVOM to the DC scale. On the ECM side of the KS harness connector, measure the voltage from the KS signal circuit to a good ground using a DVOM. On the ECM side of the KS harness connector, measure the voltage from the KS low reference circuit to a good ground using a DVOM. Is the voltage more than 4.5 volts on any circuit? If yes, go to next step. If no, go to step  7.
  6. Turn ignition switch to OFF position. Disconnect the ECM harness connectors. Check the KS signal circuit and the KS low reference circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  12. If no, go to step  9.
  7. Turn ignition switch to OFF position. Disconnect the ECM harness connectors. Check the KS signal circuit and the KS low reference circuit for an open, high resistance, or short to ground. Did you find and correct the condition? If yes, go to step  12. If no, go to step  9.
  8. Check for an intermittent and for a poor connection at the KS. Did you find and correct the condition? If yes, go to step  12. If no, go to step  10.
  9. Check for an intermittent and for a poor connection at the ECM. Did you find and correct the condition? If yes, go to step  12. If no, go to step  11.
  10. Replace KS. See KNOCK SENSOR under SENSORS & SWITCHES in REMOVAL & INSTALLATION - ION article. After replacing sensor, go to step  12.
  11. Replace ECM. See ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - ION article. Perform ECM relearn procedure. See ENGINE CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing ECM, go to next step.
  12. Using scan tool, clear the DTCs. Turn the ignition OFF for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Does the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  13. Use scan tool to observe the, CAPTURE INFO. Does the scan tool display any DTCs that you have not diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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