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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1980 (Engine Controls And Fuel - 3.6L (LCS) - Troubleshooting & Diagnosis) >> Electronic Ignition System Diagnosis >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE:
    • Do not perform this diagnostic procedure if you were not sent here from a misfire DTC or the Engine Cranks but Does Not Run diagnostic.
    • The ignition coils for each bank are fused separately. If a fuse opens or the ignition voltage circuit opens between the fuse and the splice, all the ignition coils for one bank of the engine would be inoperative. If the ground circuit opens at the engine block, the ignition coils would be inoperative for one bank of the engine.
  1. Ignition OFF, open the hood to disable the Auto-Stop function.
  2. Ignition ON, verify the scan tool hood position parameter displays Open.
    • If the hood position does not display Open, refer to DTC P254F .
  3. Ignition OFF, disconnect the harness connector at the appropriate ignition coil.
  4. Test for less than 5 Ω between each of the ground circuits listed below and ground.
    • Ignition coil ground circuit terminal 3
    • Ignition coil ground circuit terminal 4
    • If greater than the specified range, test the circuit for an open/high resistance.
    5. NOTE: The ignition circuit supplies voltage to other components. Test all circuits for a short to ground or test all components for being shorted that share the ignition circuit.
  5. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal 2 and ground.
    • If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all the components connected to the ignition voltage circuit and replace as necessary.
  6. Crank or start the engine. Test for 200-400 mV between the appropriate IC circuit terminal 1 and ground.
    • If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit/connection tests normal, replace the ECM.
    • If greater than the specified range, test the circuit for a short to voltage. If the circuit/connection tests normal, replace the ECM.
  7. If all circuits/connections test normal, replace the ignition coil.
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