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Home >> GMC >> 2006 >> Sierra 1500 HD, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1147 (Engine Controls And Fuel - 3.6L - DTC P0137 To DTC P0497) >> DTC P0201, P0202, P0203, P0204, P0205, P0206, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, or P0277 (w/LY7) >> Circuit/System Testing (w/LY7)

Circuit/System Testing (w/LY7)

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
    IMPORTANT: Disconnecting the multi-way harness connector causes DTCs P0201-P0206 fuel injector circuit open DTCs to set.
  1. Ignition OFF, disconnect the fuel injector multi-way harness connector.
  2. Ignition ON, connect a test lamp between the appropriate ignition voltage supply circuit on the ECM side of the multi-way connector and ground. Verify that the test lamp illuminates.
      IMPORTANT: The ignition voltage circuits supply voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition circuit.
    • If the test lamp does not illuminate and the fuse is open, repair the appropriate ignition circuit for a short to ground between the corresponding fuel injectors and the fuse. Replace the fuse.
    • If the test lamp does not illuminate and the fuse is OK, repair the ignition voltage circuit for an open/high resistance between the multi-way connector and the fuse.
  3. Connect a test lamp between the appropriate injector control circuit, ECM side of the multi-way harness connector, and B+. The test lamp should not illuminate.
    • If the test lamp illuminates, test the control circuit for a short to ground. If circuit/connections test normal, replace the ECM.
  4. Connect a test lamp between the appropriate injector control circuit, ECM side of the multi-way harness connector, and ground. The test lamp should not illuminate.
    • If the test lamp illuminates, test the control circuit for a short to voltage. If circuit/connections test normal, replace the ECM.
  5. Ignition ON, test for 2.6-4.6 volts between the appropriate injector control circuit, ECM side of the multi-way connector, and ground.
    • If the voltage is not within the specified range, test the control circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
  6. Remove the upper intake manifold. Refer to Upper Intake Manifold Replacement (LP1, LY7) .
  7. Disconnect the fuel injector connectors.
  8. Test for continuity between the ignition voltage circuit(s) and the appropriate fuel injector control circuit, at the fuel injector side of the multi-way harness connector, the DMM should display OL.
    • If less than OL repair the short between the ignition voltage circuit and the control circuit.
  9. Test for less than 1 ohm of resistance in the appropriate ignition voltage circuit, between the injector connector(s) and the multi-way connector.
    • If greater than 1 ohm repair the open/high resistance in the ignition voltage circuit.
  10. Test for less than 1 ohm of resistance in the suspected control circuit, between the injector connector and the multi-way connector.
    • If greater than 1 ohm repair the open/high resistance in the fuel injector control circuit.
  11. Test for continuity between appropriate fuel injector control circuit and ground. The DMM should display OL.
    • If less than OL repair the short to ground in the fuel injector control circuit.
  12. Test for continuity between the suspected fuel injector control circuit and all the other control circuits of the fuel injectors. The DMM should display OL.
    • If less than OL is measured between any of the control circuits, repair the wire to wire short between those circuits.
  13. If all circuits/connections test normal, test or replace the appropriate fuel injector(s).
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