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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1146 (Engine Controls And Fuel - 3.6L - DTC P0008 To DTC P0161) >> DTC P0135, P0141, P0155, or P0161 >> Circuit/System Testing

Circuit/System Testing

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.
  1. Ignition OFF, disconnect the harness connector at the appropriate HO2S.
  2. Ignition ON, test for B+ on the HO2S ignition voltage circuit terminal C, or terminal D of the HO2S harness connector.
    • If less than the specified value, repair the ignition voltage circuit of the HO2S heater for a short to ground or an open/high resistance.
  3. Ignition OFF, connect a test lamp between the heater control circuit terminal D, or terminal C and B+.
    • If test lamp illuminates, test the heater control circuit for a short to ground. If the circuit/connections test normal, replace the ECM.
  4. Idle the engine, and verify the test lamp illuminates or flashes.
    • If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
    5. IMPORTANT: The control circuit for the HO2S heater is pulled-up to voltage within the ECM, 2.0-3.0 volts on the control circuit is normal.
  5. Ignition ON, test for 2.0-3.0 volts between the control circuit terminal D, or terminal C and ground.
    • If not within the specified range, test the control circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
  6. If all circuits/connections test normal, test or replace the HO2S.
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