621K OEM Wheel Tractor-Scraper CAN Data Link

The following is a list of Diagnostic Trouble Codes (DTC) that are associated with the CAN data link of the machine. The CAN data link allows communication between the Transmission/Chassis ECM and other ECM modules on model 621K OEM Wheel Tractor.

The Transmission/Chassis ECM receives input or provides an output to control or monitor the following:

Speed Sensors
Temperature Sensors
Position Switches
Pressure Sensors
Solenoids
Power Relays

The Transmission/Chassis ECM is directly connected to the Main Machine CAN Data Link and the Keypad CAN Data Link.

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Table 1
Transmission/Chassis ECM (MID 27)
DTC	Code Description	System Response
246-9	Proprietary CAN Data Link - Abnormal Update Rate	Loss of data link communications with the Proprietary CAN Data Link.
247-9	J1939 Data Link - Abnormal Update Rate	Communication across the data link will be interrupted. Some machine functions will be disabled.
590-9	Engine Control Module - Abnormal Update Rate	Communication across the data link will be interrupted. Some machine functions will be disabled.
1893-2	Inertial Measurement Sensor - Data Erratic, Intermittent, Or Incorrect	Loss of data link communications with the inertial measurement sensor.
1893-9	Inertial Measurement Sensor - Abnormal Update Rate	Loss of data link communications with the inertial measurement sensor.
1893-13	Inertial Measurement Sensor - Out Of Calibration	Calibration required because sensor has been reattached or replaced.
3583-9	Switch Panel #1 - Abnormal Update Rate	Functions associated with this soft key panel will be inoperable.
3584-9	Switch Panel #3 - Abnormal Update Rate	Functions associated with this soft key panel will be inoperable.
3585-9	Switch Panel #4 - Abnormal Update Rate	Functions associated with this soft key panel will be inoperable.
3912-9	Switch Panel #5 - Abnormal Update Rate	Functions associated with this soft key panel will be inoperable.

Message Display Module

The following is a list of Diagnostic Trouble Codes (DTC) that are associated with the CAN data link of the machine. The CAN data link allows communication between the Message Display Module and other ECM modules on model 621K OEM Wheel Tractor.

The Graphical Display Module is directly connected to the Primary CAN A Data Link.

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Table 2
Message Display ECM (MID 256)
DTC	Description	System Response
247-14	SAE J1939 Data Link - Special Instruction	Control modules may be unable to communicate due to error in loading of software. This situation results in modules that are unable to communicate with each other.
590-9	Engine Control Module - Abnormal Update Rate	Communication between this module and the other modules will be intermittent.
596-9	Implement Control - Abnormal Update Rate	Communication between this module and the other modules will be intermittent.
1273-9	Chassis Control Module - Abnormal Update Rate	Communication between this module and the other modules will be intermittent.
2466-9	Engine Aftertreatment Control #1 - Abnormal Update Rate	Communication between this module and the other modules will be intermittent.
3743-9	Engine Aftertreatment Control #2 - Abnormal Update Rate	Communication between this module and the other modules will be intermittent.

Implement ECM

The following is a list of Diagnostic Trouble Codes (DTC) that are associated with the CAN data link of the machine. The CAN data link allows communication between the Implement ECM and other ECM modules on model 621K OEM Wheel Tractor.

The Implement ECM receives input or provides an output to control or monitor the following:

Temperature Sensors
Solenoids
Power Relays
Filter Bypass Circuits
Switches
Position Sensors
Pressure Sensors

The Implement ECM is directly connected to the Main Machine CAN Data Link, and the Tool Automation CAN Data Link.

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Table 3
Implement ECM (MID 82)
DTC	Code Description	System Response
84-9	Ground Speed Sensor - Abnormal Update Rate	Loss of data link communications with the ground speed sensor.
246-9	Proprietary CAN Data Link - Abnormal Update Rate	Loss of data link communications with the Proprietary CAN Data Link.
247-9	J1939 Data Link - Abnormal Update Rate	Communication across the data link will be interrupted. Some machine functions may be disabled.
590-9	Engine Control Module - Abnormal Update Rate	Communication across the data link will be interrupted. Some machine functions may be disabled.
1952-2	Chassis Angle Sensor - Data erratic, Intermittent, or Incorrect	Diagnostic code associated with the inclination sensor used for tool automation procedures. When this code is active, the Implement ECM has detected unreliable data from the sensor.
1952-9	Chassis Angle Sensor - Abnormal Update Rate	Chassis angle sensor will be unable to report data to master module.
2905-9	Switch Panel #2 - Abnormal Update Rate	Functions associated with this soft key panel will be inoperable.

Seat ECM

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Table 4
Seat ECM (MID 314)
DTC	Code Description	System Response
4544-9	Seat Control Module - Abnormal Update Rate	Communication across the data link will be interrupted. Some machine functions may be disabled.

Suspension System ECM

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Table 5
Suspension System ECM (MID 315)
DTC	Code Description	System Response
4545-9	Suspension System Control Module - Abnormal Update Rate	Communication across the data link will be interrupted. Some machine functions may be disabled.

Potential Causes and Schematics

Possible causes for an FMI 2 failure mode are:

The sensor mounting is not secure.
The sensor has failed due to an internal problem.
The vibration/shock limits of the sensor have been exceeded.

Possible causes for an FMI 9 failure mode, associated with a machine keypad, are:

Keys on the key pad were pushed simultaneously.
An open or a poor connection in the J1939 circuit.
The key pad has failed.
The energize circuit for the key pad may have failed.
The ECM has failed. This situation is unlikely.

Note: A failure of the keypad is recorded when Cat^® Electronic Technician (Cat ET) does not receive the expected soft pad information.

Note: The DTC 246-9 or 247-9 is used as a companion code and indicates a J1939 data link problem. This DTC indicates that a specific ECM has lost all communication with another ECM. Therefore, a DTC 246-9 or DTC 247-9 will never be activated as a stand-alone diagnostic code.

Possible causes for an FMI 9 failure mode, related to an ECM or module, are:

An open or a poor connection exists in the circuit for the CAN Data Link in the ECM, communication is lost.
The terminating resistors are open or the resistors are disconnected.
A wire connection is contaminated by rust or dirt.
Intermittent opens, shorts, or poor connections.
The ECM has failed. A failure of the ECM is unlikely.

Possible causes for an FMI 13 failure mode code are:

If the sensor is reattached to the machine calibration is required.
If the sensor is replaced, calibration is required.

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Illustration 1	g03348036
CAN Data Link circuit connections for 621K OEM Wheel Tractor

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Illustration 2	g03423711
Circuit connections for the Keypad CAN Data Link of the 621K OEM Wheel Tractor.

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Illustration 3	g03423709
Circuit connections for the Tool Automation CAN Data Link of the 621K OEM Wheel Tractor.

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Illustration 4	g03431720
Circuit connections for the Seat ECM connections for the 621K OEM Wheel Tractor.

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Illustration 5	g03431877
Circuit connections for the Cushion Hitch ECM connections for the 621K OEM Wheel Tractor.

Note: The diagrams above are simplified schematics for the CAN data link connections. The schematics are electrically correct, however, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic for your specific machine. Refer to the list below to identify the correct schematic for your machine.

Electrical Schematic, UENR2689 for the 621K Tractor/Scraper.

Note: A loss of power in the system to an ECM can cause the Implement ECM to activate this diagnostic code. Ensure that the ECMs with this diagnostic code are powered up before proceeding with this procedure.

Keypad Graphics

The following illustrations depict the buttons located on the switch panels found on the 621K OEM Wheel Tractor. For information on the specific function of each button, refer to the Operation and Maintenance Manual (OMM) for your specific machine:

For model 621K machines refer to Operation and Maintenance Manual, SEBU8796.

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Illustration 6	g03412521
8-button key pad located in cab of 621K

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Illustration 7	g03412526
8-button key pad located in cab and common for all 620K series

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Illustration 8	g03412527
8-button tool automation keypad

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Illustration 9	g03412529
8-button Ingress/Egress Keypad (If Equipped with Access Ladder)

Troubleshooting Procedure

Note: Poor harness connections are often the cause of a problem in electrical circuits. Before performing any troubleshooting procedure, inspect all of the connectors involved in the circuit. Verify that all of the connections in the circuit are dry, clean, secure, and in good condition. Each pin and socket in the connectors should mate correctly when the connectors are fastened together. Check for exposed wires at the connectors for nicks or abrasion. If a problem is found with any of the connections: correct the problem and verify that diagnostic code is still active, before performing the following procedures. For more information, refer to Troubleshooting, "Electrical Connector - Inspect".

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Table 6
Troubleshooting Test Steps	Values	Results
1. Identify The Active DTC Associated With The CAN Data Link	Code present	FMI 2 , diagnostic code proceed to Test Step 2. FMI 9 , diagnostic code proceed to Test Step 5. FMI 13, diagnostic code proceed to Test Step 9.
Begin Process For FMI 2 Troubleshooting HERE
2. Check The Placement Of The Pitch/Roll Sensor A. Verify that the sensor is mounted securely to the body of the machine. B. Inspect the cable connection of the sensor. Confirm that the connector is secure and not damaged.	The sensor and connector are securely in position.	OK - The pitch/roll sensor is securely mounted to the machine. Proceed to Test Step 3. NOT OK - The sensor body is not secure on the machine or the connector of the sensor is not secure. Repair: Make necessary repairs based on observations.
3. Check For An Open In The CAN Data Link A. Place the key start switch and the disconnect switch in the OFF position. B. Disconnect the machine harness connectors "J1" and "J2" from the ECM. C. At the harness connectors for the ECM, measure the resistance from wire Y787-YL(Yellow) to contact "C" of the quick disconnect. Measure the resistance from wire Y788-GN(Green) to contact "D" of the quick disconnect.	Each resistance reading is 60 (± 5) ohms.	OK - Each resistance measurement is 60 (± 5) ohms. The circuit for the CAN data link is NOT open. Proceed to Test Step 4. NOT OK - The resistance measurement is outside the acceptable range. Remove each of the resistors from the data link circuit and measure the resistance. If a resistor does not measure within tolerance of 120 ohms, replace the faulty resistor. If each resistor measures within tolerance of 120 ohms, proceed to Test Step 4. NOT OK - The resistance measurement is greater than 65 ohms. There is an open or a bad connection in the circuit for the CAN data link. Remove each of the CAN resistors from the circuit and confirm that the resistors measure 60 (± 5) ohms. Replace the resistor if not within tolerance. Repair : A resistance measurement that is greater than 5000 ohms could indicate that a wire is not connected or that a wire is open. A resistance greater than 70 ohms but less than 5000 ohms indicates a connection point is not open but is not a good connection. Verify that all data link circuit connections are clean and in good condition. Refer to the complete Electrical System Schematic of the machine. Check all of the connectors that are in the circuit for the CAN data link. Ensure that all of the connections are clean, that all of the connections are secure and that all of the connections are in good condition. Repair the machine harness or replace the machine harness.
4. Check The CAN Data Link For A Short To Ground A. The key start switch and the disconnect switch remain in the OFF position. B. Disconnect the J1 and J2 connectors from the ECM. C. Measure the resistance between wire Y787-YL(Yellow) and all pins on the machine harness. Measure the resistance between wire Y788-GN(Green) and all pins on the machine harness. Note the resistance.	The resistance readings are greater than 5000 ohms.	OK - Each resistance measurement is greater than 5000 ohms. The CAN data link is not shorted to another circuit in the machine harness. Recommendation : Contact the technical communicator at your dealership for a possible consultation with AVSpare. NOT OK - One or more of the resistance measurements is less than 5000 ohms. There is a short in the machine harness. Repair : Refer to the complete Electrical System Schematic of the machine. Examine all of the connectors in the circuit. For additional information on testing short circuits and locating short circuits, refer to Testing and Adjusting, "Wiring Harness (Short Circuit) - Test". Repair the machine harness or replace the harness.
Begin Process For FMI 9 Troubleshooting HERE
5. Check The Data Link Circuit For An Open The two CAN data link resistors are connected in parallel in the CAN data link circuit. Each resistor is a 120 ohm resistor. When a resistance measurement is taken between the data link circuits, the resistance, under normal conditions, is approximately 60 ohms with the resistors in parallel. A. Turn key start switch and disconnect switch OFF. B. Refer to Illustration 1. Disconnect the machine harness connectors, CAN data link connections from each component in the system. Leave the CAN data link resisters connected to the system. C. Inspect each machine harness connector of the CAN data link circuit for signs of dirty, loose, or corroded connector pins. Ensure that all CAN data link connections are secured in the connector, the contacts are clean, and the contacts are in good condition. D. At the ECM harness connector, measure the resistance between the CAN data link contacts.	The circuit reading is around 60 (±5) ohms.	OK - The circuit reading is around 60 (±5) ohms. The CAN data link circuit is correct. Proceed to Test Step 6. NOT OK - The resistance measurement is less than 55 ohms. Remove each of the resistors from the data link circuit and measure the resistance. If a resistor does not measure within tolerance of 120 ohms, replace the faulty resistor. If each resistor measures within tolerance of 120 ohms, proceed to Test Step 6. NOT OK - The resistance measured is greater than 65 ohms. There is an open or a bad connection in the circuit for the CAN data link. Remove each of the CAN resistors from the circuit and confirm that the resistors measure 60 (± 5) ohms. Replace the resistor if not within tolerance. Repair: There is an open or a bad connection in the CAN Data Link circuit of the machine harness. Verify that all data link connections are clean and in good condition. Repair or replace the machine harness. Note: A resistance that is greater than 65 ohms 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 ohms would indicate an open in the circuit. STOP
6. Check The Status Of The Diagnostic Code. A. Reconnect all harness connectors. Make sure that the connectors are fully sealed and the clips for each connector are fastened completely. B. Turn the key switch and the disconnect switch to the ON position. (DO NOT START THE ENGINE.) C. Check the status of the FMI 9 diagnostic code.	The FMI 9 diagnostic code is not active.	OK- The FMI 9 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection or a short at one of the connectors that was disconnected and reconnected. Resume normal operation. NOT OK- The FMI 9 diagnostic code is still active. The problem that is causing the ECM to activate the diagnostic code has not been corrected. Repair- Perform this procedure again. Verify again that there is no problem with the machine harness or the machine harness connectors. If the diagnostic code remains active or if the diagnostic code is repeatedly activated and no cause can be found, proceed to Test Step 7.
7. Flash The Latest Software To The ECM. A problem with the software program is an unlikely cause for the problem with the ECM. However, flash the latest version of ECM software to eliminate the software as a possible cause. A. In order to flash the latest software to the ECM, refer to the Troubleshooting , " ECM Software - Install" procedure that is in this manual. Note: After completing the flash program procedure, return to this procedure and proceed to the next step. B. After the latest version of software has been flashed to the ECM, turn the key switch to the OFF position. C. Start the engine. Run the engine at low idle. D. Determine if the FMI 9 diagnostic code is active.	The FMI 9 diagnostic code is not active. No new diagnostic codes or event codes have been activated.	OK - The FMI 9 diagnostic code is no longer active and no new diagnostic codes or event codes have been activated. The latest software version that has been flashed to the ECM has corrected the problem. Resume normal machine operation. STOP NOT OK - The FMI 9 diagnostic code has been activated again by the ECM. The new software program has not corrected the problem. Proceed to Test Step 8.
8. Check The Operation Of The ECM. This test step will instruct on how to install a "spare" ECM. This test step should be performed only after all of the other listed possible causes for the active diagnostic code have been thoroughly investigated. (No cause of the problem can be found.) A. Obtain a spare ECM that can be substituted for the suspected ECM. (The part number of the spare ECM MUST match the ECM that is suspected of being faulty.) B. To replace the suspected ECM with another ECM that has the latest software installed, refer to the Troubleshooting , " ECM - Replace" procedure that is in this manual. C. After completing the ECM replacement procedure, return to this procedure and proceed to the next step. D. After the spare ECM has been installed in place of the suspected ECM and the latest version of software has been flashed, start the engine. Run the engine at low idle. E. Determine if the FMI 9 diagnostic code is active.	The FMI 9 diagnostic code is not active. No new diagnostic codes or event codes have been activated.	OK - The FMI 9 diagnostic code is no longer active and no new diagnostic codes or event codes have been activated. Repair: The spare ECM that has been installed in place of the original ECM is operating correctly and no new problems have been detected. The ECM that was replaced appears to have been the cause of the problem. Return the ECM to your parts department for return to AVSpare for evaluation. Resume normal machine operation. STOP NOT OK - The FMI 9 diagnostic code has been activated by the replacement ECM. The problem has not been corrected. Repair: The activation of the original diagnostic code indicates that the original ECM was not the cause of the problem. Repeat the "CHECK THE ECM OPERATION" test step and install the original ECM back in place of the "spare" ECM that was installed. If the diagnostic code remains active or if the diagnostic code is repeatedly activated and no cause can be found, contact the Technical Communicator at your dealership for consultation with AVSpare Dealer Solutions Network (DSN). Indicate the steps that have been taken to try to find the cause of this problem. The DSN will contact qualified company personnel that can further recommend action to take in order to determine the cause of the problem. STOP
Begin Process For FMI 13 Troubleshooting HERE
9. Check The Software A. Use Cat^® Electronic Technician (Cat ET) to verify that the software versions for the data link modules are correct and compatible. B. Within Cat ET or by using the operator monitor, locate the calibration procedure for the Inertial Measurement Sensor. C. Follow the procedure from the "Calibrations" menu screen.	The proper software is installed and the calibration procedure is complete.	OK - The proper software is installed and the calibration procedure is complete. STOP NOT OK - The proper software is not installed. Repair: Flash the proper software to the appropriate ECM. Cycle the key switch to initialize the software. Ensure that the diagnostic code is no longer active. NOT OK - The calibration procedure failed. Repair: Confirm that the wire connections for the sensor are not open or damaged. Check the continuity for all wires. Perform calibration again. STOP