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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1858 (Engine Controls And Fuel - 2.2L (L61) - DTC P0031 To DTC P0172) >> DTC P0031, P0032, P0037, or P0038 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Disconnect the sensor.
  2. Ignition ON, connect a test lamp between the HO2S heater voltage supply circuit terminal D and ground. The lamp should illuminate.
    • If the lamp does not illuminate, test the voltage supply circuit for open/high resistance or a short to ground.
    • If the circuit tests normal and its fuse is open, replace the HO2S.
  3. Ignition OFF, connect a test lamp between the HO2S low control circuit terminal C and battery voltage. The lamp should not illuminate.
    • If the lamp illuminates, test the low control circuit for a short to ground. If the circuit tests normal, replace the ECM.
  4. Engine running, leave the test lamp connected from the previous step. The lamp should flash or be ON steady.
    • If the test lamp is not ON steady or flashing, then test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
    5. IMPORTANT:
    • The output driver should detect a short to voltage and turn OFF. If a resistance fault is present, the driver will remain ON and the scan tool will display more than 0 amp. Less than 10 ohms of resistance may set a DTC.
    • Performing this test may set additional DTCs.
  5. Ignition OFF, install a 30A fused jumper wire from the heater supply circuit terminal D to the heater control circuit terminal C.
  6. Engine running, observe the scan tool that the Heater parameter indicates 0.0A.
    • If more than the specified value, test the heater voltage supply and controls circuits for resistance greater than 3 ohms. If the circuits test normal, replace the ECM.
  7. If the ECM and all circuits test normal, replace the HO2S sensor.
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