This article focuses on how to solve the problem that the Carter 325C excavator engine electronic service tool will not communicate with the ECM  Possible reasons. 

2023 CAT ET 2023A 2023C & 2019C Full Service Download and Installation Service 

 1) Configuration of communication adapter. 

 2) Electrical connector. 

 3) Communication adapters and/or cables. 

 4) Supply power to the repair tool connector. 

 5) Caterpillar Electronic Technology (Cat ET) and related hardware. 

 6) Power supply to ECM.  

7) Personality module (flash file). 

 8) Caterpillar automatic data transmitter.

(2) Recommended measures. Start the engine. If the ECM does not communicate with Cat ET after the

 engine is started, continue with this procedure. If the engine will not start, see the "Crank the Engine, 

But the Engine Does Not Start" section. If engine cranking does not work, see the "Engine Does Not 

Crank" section.  

12.2021 Caterpillar ECM ECU Flash Files Full Set Download 

1) Configuration of communication adapter. 

 ①Select "Preferences" in the "Utilities" menu on Cat ET. 

 ② Confirm that the correct "Communications Interface Device" has been selected. 

 ③ Check whether the correct communication adapter "Port (hole)" has been selected. NOTE: The most commonly used hole is "COM1". 

 ④ Check if any hardware and communication adapter use the same hole. If any device is configured to use the same hole, exit or close the software program for that device. 

 2) Electrical connector. Check that ECM connectors JI/P1 and J2/P2 and service tool connectors are 

installed correctly. 3) Communication adapters and/or cables.  

① If you are using Communication Adapter II, confirm that the microprogramming language and 

driver 

files of the communication adapter are the latest. If the microprogram language and driver files are

 incompatible, the communication adapter cannot communicate with Cat ET. 

 ② Disconnect the communication adapter and cable from the service tool connector. Then connect the 

communication adapter back to the service tool connector. 

 ③Confirm that the cable used between the communication adapter and the service tool connector is 

correct. 

 4) Supply power to the repair tool connector. Verify battery voltage between service tool connector 

terminals A and B. If the communications adapter does not receive power, the display on the 

communications adapter will be blank.

CAT Caterpillar ET 3 Diagnostic Adapter 317-7485/478-023 Diagnostic Tool-high quality 

  5) Caterpillar Electronic Technology (Cat ET) and related hardware. To confirm that the Cat ET and 

related hardware are not faulty, connect the Cat ET to another engine. If the same problem occurs on 

another engine, check the CatET and related hardware to determine the cause of the failure.

  6) Supply power to the ECM. Check the power to the ECM, see the "Testing the Power Supply 

Circuit" section. Note: If the ECM does not receive battery voltage, the ECM cannot communicate. 

 7) Personality module (flash file). Verify that the correct personality module is properly installed in the 

ECM. Note: The personality module in the new ECM is blank. The engine will not start or 

communicate until the personality module is flashed, see the Flash Programming section.

  8) Caterpillar automatic data transmitter. To diagnose and troubleshoot problems on a Caterpillar 

automatic data transmitter, see the "Testing the CAT Data Transmission Circuit" section.