Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the HO2S 1.
- Ignition ON, load test for B+ between the ignition voltage circuit terminal 3 and ground.
- If less than the specified range, repair the ignition voltage circuit for a short to ground, or an open/high resistance.
- Test for 4.6-5 volts between the heater control circuit terminal 4 and ground.
- If less than the specified range, test the heater control circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, test for 2.5-3.5 volts between the high signal circuit terminal 1 and ground.
- If less than the specified range, test the high signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.
- If greater than the specified range, test the high signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Test for 2-3 volts between the low signal circuit terminal 5 and ground
- If less than the specified range, test the low signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- If greater than the specified range, test the low signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- If all conditions test normal, replace the HO2S 1.