Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
All modules must be powered down or misdiagnosis may result.
- Ignition OFF, disconnect the harness connector at the appropriate B52 Heated Oxygen Sensor.
- Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 Ω between the low reference circuit terminal A and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, verify the appropriate scan tool HO2S voltage parameter is approximately 450 mV.
- If less than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.
- If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
- Ignition ON, install a 3 A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool HO2S voltage parameter is less than 60 mV.
- If greater than the specified range, test the signal circuit for an open/high resistance. If the circuits test normal, replace the K20 Engine Control Module.
- Verify none of the following conditions exist:
- Lean fuel injectors-Refer to Fuel Injector Diagnosis (CH47976) , Fuel Injector Diagnosis (J39021 or Scan Tool)
- Water intrusion in the HO2S harness connector
- Low fuel system pressure-Refer to Fuel System Diagnosis (Without FPCM) , Fuel System Diagnosis (FPCM)
- Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis
- Exhaust leaks
- Engine vacuum leaks
- Contaminated HO2S - Silicon
- An engine mechanical condition- Symptoms - Engine Mechanical
- If you find any of the above conditions, repair as necessary.
- If all circuits test normal, replace the appropriate B52 Heated Oxygen Sensor.