The SPN 973 FMI 9 fault code typically indicates an issue with the J1939 EBC1 (Engine Brake Switches) being missing. Here are some steps to troubleshoot this fault:

  1. Check for Multiple Codes: If other codes like CPC SPN 168/FMI 0/14/18 (Battery Voltage) or MCM SPN 625/FMI 9 are present, address those first.
  2. Reprogramming Check: If the CPC (Common Powertrain Controller) has been recently reprogrammed, ensure the CPC Group PGR001 parameter “EBC1 Source Address SAE J1939” is configured correctly.
  3. Module Communication: Use ServiceLink to determine which modules are configured for the vehicle and their communication status. Follow the appropriate troubleshooting procedures for the affected module.

If you need more detailed guidance, it might be helpful to consult a professional technician or refer to the specific troubleshooting guides for your vehicle model.