Circuit/System Testing
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) or Fuel Injector Diagnosis (J39021 or Scan Tool)
- Water intrusion in the B52 HO2S harness connector
- High fuel system pressure-Refer to Fuel System Diagnosis (w/o FPCM) or Fuel System Diagnosis (FPCM)
- Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (Special Tool)
- 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.