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Home >> Saab >> 2006 >> 9-7X 4.2i >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 4.2L - Troubleshooting >> Electronic Ignition (EI) System Diagnosis >> Circuit/System Testing

Circuit/System Testing

IMPORTANT: Verify that the engine is in good mechanical condition before continuing with this diagnostic.
  1. Turn ON the ignition.
  2. Inspect the fuse that supplies voltage to the ignition coils.
    • If the fuse is open, test the spliced circuits and the individual ignition coils for a short to ground.
  3. Disconnect the affected ignition coil.
  4. Connect a test lamp between the ignition voltage circuit and a good ground.
  5. With the test lamp still connected, measure for battery voltage between the ignition voltage circuit and a good ground.
    • If the voltage is not within 0.5 volt of battery voltage, repair the high resistance or the open in the ignition voltage circuit.
  6. Turn OFF the ignition, and all electrical accessories. Allow sufficient time for all of the control modules to power down before taking a resistance measurement.
  7. Measure for a proper value of less than 5 ohms of resistance between the ground circuit of the affected ignition coil and a good ground.
    • If the resistance is more than 5 ohms, repair the high resistance or the open in the ground circuit.
  8. Exchange the affected ignition coil with the ignition coil of a good cylinder.
  9. Start the engine and observe the scan tool.
    • If the misfire transfers with the suspect ignition coil, replace as needed.
    • If the misfire does not transfer with the suspect ignition coil, review the component testing procedures below and replace the spark plug, if needed.
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