Circuit/System Testing

Testing the Ignition 1 Signal Circuit

1. Ignition ON, verify that B+ is available to both test points of the inline fuse from the ignition main relay to the ECM.
   • If B+ is only available on one test point of the fuse, test the ignition 1 voltage circuit from the fuse to the ECM for a short to ground. If the circuit tests normal, replace the ECM.
   • If B+ is not available on either test point of the fuse, replace the underhood fuse block.
     IMPORTANT: A resistance of 5 ohms or greater in the circuit will cause the DTC to set.
2. Ignition OFF, disconnect the ECM C1 connector.
3. Ignition ON, verify that B+ is available at C1-19.
   • If B+ is not available, test the ignition 1 voltage circuit for an open/high resistance condition. If the circuit tests normal, replace the ECM.
4. If all circuits test normal, replace the ECM.

Testing the EC Ignition Relay Feedback Circuit

1. Ignition OFF, remove the powertrain relay from the underhood fuse block.
   IMPORTANT: A resistance of 5 ohms or greater in the circuit will cause the DTC to set.
2. Ignition ON, connect a 3A fused jumper wire from B+ to the powertrain ignition 1 voltage circuit terminal. Verify that the EC Ignition Relay Feedback parameter displays B+ on the scan tool.
   • If the scan tool parameter is less than the specified value, test the ignition 1 voltage circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.