WORM 3B9970 - Caterpillar

Probable Causes
Electronic Control Module (ECM)
Data Link Communication
Electrical Connectors and the WiringRecommended Actions
Table 1
Troubleshooting Test Steps Values Results
1. Check for Communications Between Caterpillar Electronic Technician (ET) and the ECM
A. Connect Cat ET to the service tool connector.
B. Restore electrical power to the ECM.
C. Establish communications between Cat ET and the ECM.
ECM
Result: Communications is established between Cat ET and the ECM.
The ECM is operating properly.
Proceed to the next step.
Result: Cat ET will not communicate with the ECM.
Proceed to Troubleshooting, "Electronic Service Tool Does Not Communicate" for information related to troubleshooting this problem.
2. Check the Data Link Communication
A. Verify communications over the Cat Data Link and the CAN data link, if applicable.
Data Link
Result: A problem is found in the data link.
Repair: Perform any necessary repairs. Refer to Troubleshooting, "Data Link - Test" if a problem with communications via the data links is suspected.
If the problem is not resolved, proceed to the next step.
3. Inspect the Electrical Connectors and the Wiring
A. Remove electrical power from the ECM.
B. Proceed to Troubleshooting, "Electrical Connectors - Inspect" for information related to checking for harness and connector problems.
Connectors
Result: Harnesses and connectors appear to be OK.
Result: There is a problem with the connectors and/or wiring.
Repair: Perform the necessary repairs to the connectors and/or wiring.