303.5E2 CR Mini-HEX Machine ECM Caterpillar

CAN Data Link - Test

Usage:

Machine ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the CAN Data Link of the machine.

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Table 1
Machine ECM (MID 39)
DTC	Code Description	System Response
247-9	SAE J1939 Data Link : Abnormal Update Rate	Machine components that directly communicate on this link will be unavailable. (See machine schematic.)
590-9	Engine Control Module : Abnormal Update Rate	Machine components that directly communicate on this link will be unavailable. (See machine schematic.)
2448-9	Graphical Display Module : Abnormal Update Rate	Machine components that directly communicate on this link will be unavailable. (See machine schematic.)

Each CAN Data Link circuit is an input and output of select electronic control modules. The data link is designed to carry communications between the electronic control modules. The data link consists of internal control circuits and the connecting harness wiring.

Possible Causes for an FMI 9 diagnostic code are:

The wrong software is installed on an ECM.
An improper key was used.
The ECM is operating intermittently.
Terminating resistors on the J1939 data link are faulty.
An open or a poor connection in the data link circuit.
Short in the data link circuit.
The ECM or smart device is not powering up or powering down properly.
Lack of key switch input to an ECM or smart device (where applicable).
The energize circuit for the MSS Key Reader may have failed.
Excessive noise on the data link circuit.
The ECM module or smart device has failed. This condition is unlikely.

Note: A loss of power in the system to an ECM can cause the Machine ECM to activate this diagnostic code combination. Ensure that the ECM modules associated with this diagnostic code are powered up before beginning this procedure.

The FMI 9 code means that the ECM has lost all communication with another module.

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Illustration 1	g06035792

Note: The diagram above is a simplified schematic of the Machine ECM connections. The schematic is electrically correct. However, not all of the possible harness connectors are included. Refer to the latest revision of Electrical Schematic, UENR6662 for the complete schematic.

Diagnostic Trouble Code Procedure

Note: Prior to beginning this procedure, inspect the harness connectors for this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Inspect the connections for signs of moisture, rust, or damaged pins. Verify that all connections in the circuit are clean, secure, and in good condition. Check the wiring for pinch points or abrasions. Look for and repair areas that indicate wires are exposed. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing a troubleshooting procedure.

Identify the active FMI code associated with the components.
Determine which code is present and use the list below to determine which procedure to follow.

FMI 9 diagnostic code, proceed to Table 2.

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Table 2
FMI 9 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Verify The Hardware And The Software Part Numbers⁽¹⁾ A. Verify that the following information is correct: -The part number of the flash software for the ECM is correct. -The part number of the ECM is correct. -The part numbers of the sensors are correct. -The part numbers of the data link resistors are correct.	All the part numbers are correct	OK - All the part numbers are correct. Proceed to Test Step 2. NOT OK - All the part numbers are not correct. Repair: The ECM has the wrong part number or incorrect flash software installed. Flash the correct software or replace the ECM (or sensors) with a module that has the correct part number. Refer to the Troubleshooting, "ECM - Flash Program" section for additional information Proceed to Test Step 9.
2. Inspect The Harness Connections A. Turn key start switch and disconnect switch to the OFF position. B. Inspect all harness connections related to the CAN data link. Make sure that the connectors are clean and tight. C. Check the connectors for proper mating. Ensure that all the seals are present and in place. D. Check the harness for signs of damage or abrasion. E. Check the wires at the connector. Ensure that the wires are secured tightly into the connector. Take care not to pull the wire out of the connector. F. Check the exposed wires at the connectors for nicks or signs of abrasion. G. Check for moisture inside the connector.	The machine harness connectors are tight and free of corrosion.	OK - The machine harness connectors are tight and free of corrosion. Proceed to Test Step 4. NOT OK - The machine harness connectors are in need of repair. Repair: Repair or replace the machine harness. Proceed to Test Step 9.
3. Check The Voltage Of The Data Link A. Turn the key start switch and the disconnect switch to the ON position. B. Connect Cat^® Electronic Technician (Cat ET) Service Tool. Verify that the ECM module has logged communication diagnostics. At each component that is not communicating, use an electrical spoon to measure the voltage. One at a time, measure the voltage of the CAN data link wires to frame ground.	The reading is 0.5V to 4.5V on each wire.	OK - The voltages of the wires for the data links are correct. Proceed to Test Step 6. NOT OK - The voltage is greater than 4.5 V. Proceed to Test Step 7. NOT OK - The voltage is less than 0.5 V. Proceed to Test Step 4.
4. Check For Short To Ground In The Data Link A. The key start switch and disconnect switch remain in the OFF position. B. Disconnect the machine harness connectors from all modules that use the suspect CAN data link. C. At the machine harness for the Machine ECM, measure the resistance between frame ground and the positive CAN connector contact of the circuit. D. At the machine harness for the Machine ECM, measure the resistance between frame ground and the negative CAN connector contact of the circuit.	The reading is greater than 5K Ω.	OK - The harness circuit resistance is correct. Proceed to Test Step 5. NOT OK - A reading is less than 5 Ω. The machine harness has failed. Repair: There is a short between frame ground and the contacts of the CAN data link circuit in the machine harness. Repair or replace the machine harness. Note: A resistance greater than 5 Ω but less than 5K Ω indicates a loose or corroded connection in the circuit. A resistance measurement greater than 5K Ω indicates an open in the circuit. Proceed to Test Step 9.
5. Check For A Short Between The Data Link Wires A. The key start switch and the disconnect switch remain in the OFF position. B. Disconnect the terminating resistors if the resistors are a part of the circuit. C. Measure the continuity between the data link wires.	The reading is greater than 5K Ω.	OK - The resistance measurement is correct. Proceed to Test Step 6. NOT OK - The resistance measurement is not correct. The wires for the data link are shorted together. Repair: Repair the machine harness or replace the harness. Proceed to Test Step 9.
6. Check The Terminating Resistors A. The key start switch and the disconnect switch remain in the OFF position. B. The terminating resistors remain disconnected. C. Check the terminating resistor connectors for the following: -Moisture -Corrosion -Damaged Terminals -Loose Connections D. Measure the resistance between terminal A and B of each terminating resistor that was removed from the CAN circuit.	The reading is approx. 120 Ω.	OK - Both resistance measurements are approximately 120 Ω. The terminating resistors have not failed. Reinstall the terminating resistors. Proceed to Test Step 7. NOT OK - One or both resistance measurements are not approximately 120 Ω. At least one of the resistors is not functioning properly. Repair: Replace the terminating resistor or resistors that have failed. Reinstall the terminating resistor that has not failed. Proceed to Test Step 9.
7. Check For A Short To +Battery Circuit In The Data Link A. The key start switch and disconnect switch are in the OFF position. B. All related modules remain disconnected from the machine harness. C. At the machine harness connector for the Machine ECM, measure the resistance between the connector contact for the +Battery and the positive CAN connector contact. D. At the machine harness connector for the Machine ECM, measure the resistance between the connector contact for the +Battery and the negative CAN connector contact.	The reading is greater than 5K Ω.	OK - The harness circuit resistance is correct. Proceed to Test Step 8. NOT OK - A reading is less than 5 Ω. The machine harness has failed. Repair: There is a short between the +Battery circuit and one of the CAN data link circuits in the machine harness. Repair or replace the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 9.
8. Check The Data Link For An Open Note: Two 120 Ω resistors should be on the CAN Data Link. A resistance of 60 Ω should be found at any point on the data link with the resistors installed. A. The key start switch and disconnect switch are in the OFF position. B. Use an electrical spoon to connect to the back of the harness connector for each ECM that has communication issues. C. Measure the resistance across the CAN line at each connector to find the open wire. If the resistance measurement is 60 Ω, that connector does not have an open between either terminating resistor. If the resistance measurement is 120 Ω, there is an open at that connector, between one of the terminating resistors. If the resistance is greater than 5K Ω, there is an open between that connector and both terminating resistors. If there is a measurement of 40 Ω, there is an extra terminating resistor somewhere on the line. Once the section of harness containing the open is isolated, repair or replace the machine harness.	All resistance measurements are between 55 and 65 Ω	OK - The resistance measurements are correct. Proceed to Step 9. NOT OK - At least one resistance measurement is greater than 65 Ω. If the resistance is approximately 115 Ωto 125Ω. There is an open in the harness. Repair: Repair or replace the machine harness. Proceed to Test Step 9. NOT OK - At least one resistance measurement is less than 55 Ω. Repair: Look for the source of the short by disconnecting the terminating resistors and check the resistance again. If the resistance is still under 55 Ω, continue disconnecting components from the CAN circuit until the resistance rises. If everything is disconnected from the CAN circuit, and the resistance still is less than 55 Ω the harness has failed. Repair or replace the machine harness. Proceed to Test Step 9.
9. Check If The Diagnostic Code Remains A. Reconnect all harness connectors. Return machine to normal operating condition. B. Turn the key start switch and the disconnect switch to the ON position. C. Clear all diagnostic codes. D. Operate the machine. E. Stop the machine and engage the safety lock lever. F. Check if the diagnostic code is active.	The diagnostic code is no longer present.	OK - The diagnostic code does not exist currently. The initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Resume machine operation. STOP. NOT OK - The diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM may require replacement. Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time. Follow the steps in Troubleshooting, "ECM - Replace" if the ECM needs to be replaced. STOP.