Circuit/System Testing
WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the appropriate ignition coil.
- Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal D and ground.
- If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all the components connected to the ignition voltage circuit and replace as necessary.
- Crank or start the engine. Test for 200-400 mV between the appropriate IC circuit terminal C and ground.
- If less than the specified range, test the IC circuit for a short to ground or an open/high resistance. If the circuit/connection tests normal, replace the ECM.
- If greater than the specified range, test the IC circuit for a short to voltage. If the circuit/connection tests normal, replace the ECM.
- Ignition OFF, connect a test lamp between the low reference circuit terminal B and B+. The test lamp should illuminate.
- If the test lamp does not illuminate, test for an open/high resistance in the low reference circuit. If the circuit/connection tests normal, replace the ECM.
- Connect a test lamp between the ground circuit terminal A and B+. The test lamp should illuminate.
- If the test lamp does not illuminate, test for an open, or high resistance in the ground circuit.
- If all circuits/connections test normal, replace the ignition coil.
NOTE:
The ignition circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition circuit.