3176C, 3406E and 3456 Industrial Engines Troubleshooting – ECM Does Not Communicate with Other Modules

Probable Causes


  • Electronic Control Module (ECM) 
  • Electrical connectors 
  • Data link communications 
  • Keyswitch power 

Recommended Actions


Connect Caterpillar Electronic Technician (ET). If the ECM does not communicate with Cat ET, refer to service Troubleshooting, “Electronic Service Tool Does Not Communicate”.

Note: This application utilizes dual data link communications for communicating with Cat ET. Some functionality will not be available if a single data link is being used for communications with the ECM.

Electrical Connectors

Check for correct installation of the J1/P1 and J2/P2 ECM connectors. Check for correct installation of all other applicable connectors. Refer to service Troubleshooting, “Electrical Connectors – Inspect”.

Data Link Communications

Verify communications over the Cat Data Link and the CAN data link. Refer to Troubleshooting, “Data Link – Test” if a problem with communications via the data links is suspected.

Keyswitch Power

Ensure that keyswitch power is being provided to all of the modules that are on the application. Refer to Troubleshooting, “Electrical Power Supply – Test” for information that is related to troubleshooting the engine’s keyswitch circuit.

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