Circuit/System Testing
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the HO2S 1.
- 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.
- Test for 50-90 mV between the input pump current circuit terminal 6 and ground.
- If less than the specified range, test the input pump circuit and pump current 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 input pump circuit and pump current circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- If all circuits test normal, replace the HO2S 1.
IMPORTANT:
The input pumping current circuit and the pump current circuit are connected internally within the ECM. If there is a condition with one of the circuits, the other circuit will be affected.