Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 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 HO2S.
- 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 B52 HO2S 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 ECM.
- If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
- Ignition ON, install a 3 A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool B52 HO2S 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 ECM.
- Verify none of the following conditions exist:
- Rich fuel injectors-Refer to Fuel Injector Diagnosis (CH47976) , Fuel Injector Diagnosis (J39021 or Scan Tool)
- Water intrusion in the B52 HO2S harness connector
- High 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
- Fuel saturation of the evaporative emission (EVAP) canister
- If you find any of the above conditions, repair as necessary.
- If all circuits test normal, replace the appropriate B52 HO2S.