Circuit/System Testing
WARNING: This page is about a different car, the 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Ignition OFF, disconnect the harness connector at the HO2S 1.
- Ignition ON, verify that a test lamp illuminates between the HO2S 1 heater voltage supply circuit terminal 4 and ground.
- If the test lamp does not illuminate, test the HO2S 1 heater voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and the HO2S 1 heater voltage supply circuit fuse is open, test all components connected to the fuse and replace as necessary.
- Ignition ON, measure for approximately 4.9 volts between the HO2S 1 heater low control circuit terminal 3 and ground.
- If less than the specified value, test the HO2S 1 heater low control circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the ECM.
- If more than the specified value, test the HO2S 1 heater low control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Engine OFF, install a test lamp between the HO2S 1 voltage supply circuit terminal 4 and the HO2S 1 heater low control circuit terminal 3. Allow the ECM to power down.
- Engine RUNNING, the lamp should be ON steady.
- If the test lamp is not on steady, replace the ECM.
- If the ECM and all circuits test normal, replace the HO2S 1.