Using Caterpillar Electronic Technician to Determine Diagnostic Trouble Codes
Connect the Caterpillar Electronic Technician (ET) to the vehicle. Turn the key switch to the RUN position. Start the Cat ET. The Cat ET will initiate communications with the Electronic Control Units on the vehicle. After communication has been established, the Cat ET will list the Electronic Control Units. Choose the desired Electronic Control Unit. After the diagnostic trouble codes have been determined with the Cat ET, see the test procedure for the corresponding diagnostic trouble code.
ReferenceTroubleshooting, "Service Tools"
Active Diagnostic Trouble Codes
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Typical Cat ET screen for active diagnostic trouble codes | |
The following procedures may cause new diagnostic trouble codes to be logged. Therefore, before any procedures are performed make a list of all the active diagnostic trouble codes in order to determine the system problems. Clear the diagnostic trouble codes that were caused by the procedure, when each procedure is complete.
Note: Before performing a procedure, always check all the circuit breakers. Repair the cause of any circuit breaker that is tripped.
A screen is provided in Cat ET for active diagnostic trouble codes. The screen will display the diagnostic trouble codes that are active. Active diagnostic information shall include a component identifier (SPN), a failure mode identifier (FMI) and a text description of the problem.
Logged Diagnostic Trouble Codes
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Typical Cat ET screen for logged diagnostic trouble codes | |
A screen is provided in Cat ET for logged diagnostic trouble codes. The screen will display diagnostic trouble codes that are logged. The Cat ET will log diagnostic trouble codes that are intermittent. The logged diagnostic data shall include a component identifier (SPN), a failure mode identifier (FMI), and a text description of the problem. Also, the logged diagnostic data shall include the number of occurrences of the problem and two time stamps. The time stamp displays the first occurrence of the problem and the time stamp displays the most recent occurrence of the problem.
Diagnostics are logged in non-volatile memory. On powerup, the ECU will clear any diagnostic trouble codes that have not been detected or active within the last 150 hours of vehicle operation.
Connecting Cat ET and the Communication Adapter II
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(1) Personal computer (PC) (2) 196-0055 Adapter Cable As (3) 275-5121 Communication Adapter As (4) 332-7381 Adapter Cable As | |
Note: Items (2) , (3) , and (4) are part of the 171-4400 Communication Adapter II Gp .
Use the following procedure to connect Cat ET and the Communication Adapter II.
- Turn the keyswitch to the OFF/RESET position. If the key switch is not placed in the OFF/RESET position, the engine may start.
- Connect cable (2) between the "COMPUTER" end of communication adapter (3) and the RS232 serial port of PC (1) .
- Connect cable (4) between the "DATA LINK" end of communication adapter (3) and the service tool connector.
- Turn the keyswitch to the ON position. If Cat ET and the communication adapter do not communicate with the Engine Control Unit (ECU), proceed to the next Test Step.
Electronic Service Tool Will not Communicate with ECU
Probable Causes
- Configuration for the communications adapter
- J1/P1 connectors for the Engine Control Unit (ECU)
- Communication adapter and/or cables
- Electrical power supply to the service tool connector
- Caterpillar Electronic Technician (ET) and related hardware
- Electrical power supply to the ECU
- Override switches
- J1939 data link
Recommended Actions:
1. Electrical Power Supply to the Service Tool Connector
Verify that the battery voltage is present between terminal A and terminal B of the service tool connector. If the commmunication adapter is not receiving power, the communication adapter's power light will not be on. Proceed to Test Step 2 if the power light is not illuminated. Try turning the key off and shutting down Cat ET if the communication adapter is powered but is still not communicating.
2. Communication Adapter and/or Cables
Usure all of the connections are tight and dry. If you are using a 171-4401 Communication Adapter Assembly , ensure that the firmware and the software files for the adapter are the most current that are available. If the firmware and the software do not match, the communication adapter will not communicate with Cat ET. Proceed to Test Step 3.
3. Cat ET and Related Hardware
In order to elminate Cat ET and the related hardware as the problem, connect Cat ET to a different engine. If the same problem occures on a different engine, check Cat ET and the related hardware in order to determine the cause of the problem. If Cat ET and the hardware are good, proceed to Test Step 4. If you cannot gain communications on another machine, proceed to Test Step 8.
4. J1/P1 ECU Connectors
Check the J1/P1 ECU connectors for the following problems:
- Proper torque
- Cleanliness of the terminals
- Wires and terminals are properly installed into the connector.
Refer to Testing and Adjusting, "Electrical Connectors - Inspect" for additional information. Proceed to Test Step 5.
5. Electrical Power Supply to the ECU
If the ECU is not receiving battery voltage, The ECU will not communicate. Check the electrical power to the ECU. Proceed to Test Step 6 if there is no power to the ECU.
6. Override Switches
Verify that there are no aftermarket devices that are preventing battery voltage from reaching the ECU. Some type of override switch is interrupting the power to the ECU if the following conditions are true:
- Communication occurs when the engine is running
- No communication occurs when the engine is not running and the key switch is ON
Try starting the engine and gaining communications. This procedure may solve the communication problem. If the problem is not fixed, proceed to Test Step 7.
Perform the following procedure:
1. Turn the key switch to the OFF position.
2. Discoonect Cat ET.
3. Turn the key switch to the ON position.
4. Connect Cat ET.
7. J1939 Data Link
Troubleshoot the J1939 data link for possible problems. Refer to troubleshooting the "data link".
8. Configuration for the Communications Adapter
1. Access "Preferences" under the "Utilities" menu on Cat ET.
2. Verify that the correct "Communications Interface Device" is selected.
3. Verify that the correct "Port" is selected for use by the communication adapter. The most commonly used port is "COM 1".
4. Check for any hardware that is utilizing the same port as the communications adapter. If any devices are configured to use the same port, exit or close the software programs for that device.