System Diagnosis - Backup Power Circuit

1. Disconnect battery ground cable, then the positive cable.
2. Disconnect ECM connectors.
3. Connect a suitable ohmmeter between terminal 13 and disconnected battery positive cable. Ensure ohmmeter reading is ``0'' and continuity exists.
4. If ohmmeter reading is not zero check circuit for open or poor contact.
5. Reconnect battery positive, then the negative cables to battery.