Circuit/System Testing

WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.

Ignition OFF, disconnect the harness connector at the appropriate HO2S.
Ignition ON, test for B+ on the HO2S ignition voltage circuit terminal C of the HO2S harness connector.
- If less than the specified value, repair the ignition voltage circuit for an open/high resistance.
Ignition OFF, connect a test lamp between the heater control circuit terminal D and B+.
Idle the engine, and verify the test lamp illuminates or flashes with bright intensity.
- 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.
Ignition ON, verify that the applicable HO2S voltage parameter is between 350-500 mV.
- If less than the specified value, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM.
- If greater than the specified value, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
Install a 3A fused jumper wire between the signal circuit terminal B and ground. Verify the HO2S voltage parameter is less than 60 mV.
- If greater than the specified value, test the signal circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
Connect a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the HO2S voltage parameter is less than 60 mV.
- If greater than the specified value, test the low reference circuit for an open/high resistance or for a short to voltage. If the circuit/connections test normal, replace the ECM.
Verify that none of the following conditions exist:
- The HO2S is loose
- Lean or rich fuel injectors - Refer to FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL or FUEL INJECTOR BALANCE TEST WITH TECH 2 .
- Water intrusion in the HO2S harness connector
- Low or high fuel system pressure - Refer to FUEL SYSTEM DIAGNOSIS .
- Fuel that is contaminated - Refer to ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS (W/O SPECIAL TOOL) and ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS (W/ SPECIAL TOOL) .
- Fuel saturation of the evaporative emission (EVAP) canister
- Exhaust leaks near the HO2S
- Engine vacuum leaks
  - If you find any of the above conditions, repair as necessary.
If all circuits/connections test normal, replace the applicable HO2S.