Testing the Ignition 1 Signal Circuit
- 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.
- Ignition OFF, disconnect the ECM C1 connector.
- 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.
- If all circuits test normal, replace the ECM.
IMPORTANT:
A resistance of 5 ohms or greater in the circuit will cause the DTC to set.