Circuit/System Testing
WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
- Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description .
- Ignition ON, verify the scan tool hood position parameter displays Open.
- If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.
- Ignition OFF, disconnect the powertrain relay.
- Ignition ON, verify that a test lamp does not illuminate between the powertrain relay controlled output circuit terminal and ground.
- If the test lamp illuminates, test the powertrain relay controlled output circuit for a short to voltage.
- Ignition OFF, verify that a test lamp illuminates between the powertrain relay coil voltage supply circuit terminal and ground.
- If the test lamp does not illuminate, test the powertrain relay coil voltage supply circuit for a short to ground or an open/high resistance.
- Verify that a test lamp illuminates between the powertrain relay switch voltage supply circuit terminal and ground.
- If the test lamp does not illuminate, test the powertrain relay switch voltage supply circuit for an open/high resistance.
- Disconnect the ECM.
- Ignition ON, verify that a test lamp illuminates between ECM connector terminal X1-19 and ground.
- If the test lamp does not illuminate, test the ignition 1 relay controlled output circuit for a short to ground or open/high resistance.
- If the circuit tests normal and its fuse is open, replace the ECM.
- Ignition OFF, connect the harness connector at the ECM.
- Ignition ON, connect a jumper wire between the powertrain relay voltage supply circuit terminal and the powertrain relay controlled output circuit terminal. Verify the EC Ignition Relay Feedback parameter indicates battery positive voltage.
- If not the specified value, test the powertrain relay controlled output circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, replace the ECM.
- If all circuits test normal, replace the powertrain relay.