D7E Track-Type Tractor Caterpillar

Note: The Generator ECM and the Motor ECM each monitor the phase current for the six power transistors located inside the Power Inverter. These current sensors cannot be accessed inside the Power Inverter and are not serviceable. The Motor ECM and Generator ECM continuously monitor the phase current from each of the power transistors via the Control Harness. If either the Motor ECM or the Generator ECM has an electrical fault, the Machine ECM will disable the Power Train.

Illustration 1	g03851507

Generator ECM

The following is a list of Diagnostic Trouble Codes (DTCs) associated with the current sensors of the Power Inverter that are monitored by the Generator ECM.

Table 1

Generator ECM
DTC	Code Description	System Response
2792-3	Generator- Phase A Current Sensor: Voltage Above Normal	The Power Train will be disabled.
2792-4	Generator- Phase A Current Sensor: Voltage Below Normal	Refer to FMI 4 table below.
2793-3	Generator Phase B Current Sensor: Voltage Above Normal	The Power Train will be disabled.
2793-4	Generator Phase B Current Sensor: Voltage Below Normal	Refer to FMI 4 table below.
2794-3	Generator Phase C Current Sensor: Voltage Above Normal	The Power Train will be disabled.
2794-4	Generator Phase C Current Sensor: Voltage Below Normal	Refer to FMI 4 table below.

Possible causes for an FMI 3 diagnostic code are:

• Poor connections or faulty connections in the Control Harness connectors

• The sensor circuit is shorted to a higher voltage circuit in the Control Harness.

• The current sensor has failed.

• The ECM has failed. ECM failure is unlikely.

Possible causes for an FMI 4 diagnostic code are:

• Poor connections or faulty connections in the Control Harness connectors

• The sensor signal circuit is open in the Control Harness.

• The sensor signal circuit is shorted to either frame ground or to a ground circuit in the Control Harness.

• The current sensor has failed.

• The ECM has failed. ECM failure is unlikely.

The following table lists the logic the ECM will use when low voltage conditions exist in one or more of the current sensor circuits.

Table 2

How The Generator ECM Handles FMI 4 (Low Voltage) Current Sensor Conditions
Open circuit or short to ground condition (FMI 4, low voltage)	ECM Response	Machine Operation Response
Condition exists in one of the three current sensor input circuits.	The ECM detects the condition and logs a DTC for the involved sensor.	Machine continues to operate.
Condition exists in two of the three current sensor input circuits.	Due to internal limitations, the ECM will not detect that the second sensor circuit voltage is low.	Machine continues to operate for a time period. Most likely will result in a "high voltage" or "high current " Event to be activated by the Generator ECM or the Motor ECM which will disable power train operation.
Condition exists in all three of the current sensor input circuits.	The ECM will detect that all three sensor circuits are in a low voltage condition.	Power train operation will be disabled. An FMI 4 DTC will be activated for each of the three current sensors. An EID 2169 may also be triggered.

Note: As noted in the table, the ECM cannot detect that two separate current sensor circuits have a low voltage condition at the same time. Consequently, if an EID 655 (DC Power Bus Voltage High) or an EID 657, 668, 669, 670, 675, 676 (Phase Current High) is activated by the Generator ECM or the Motor ECM, the cause of the active EID could be that two current sensor circuits are in a low voltage condition. If either of these scenarios occur, check all three of the current sensor circuits for open circuits or short to ground circuit conditions to determine if two current sensor circuits have the low voltage condition.

The Generator phase current sensors are supplied power from the Generator ECM positive (+)15 VDC and the negative (-)15 power supplies. If the Generator ECM has activated DTC 3049 (15 V power supply) or DTC 3207 (-15 V power supply), correct the problem causing these codes before performing this procedure.

The Generator ECM supplies two connections for each power supply to the Power Inverter. The positive (+)15 V power supply is internally connected in each control and the negative (-)15 V power supply is internally connected in each ECM. Both connections for either power supply would have to fail for the power to the current sensor to be interrupted.

Illustration 2	g03822634
Generator ECM current sensor connections

Note: The diagram above is a simplified schematic of the Generator ECM and the current sensor connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic, UENR4073 for the complete schematic.

Motor ECM

The following is a list of DTCs associated with the current sensors of the Power Inverter that are monitored by the Motor ECM.

Table 3

Motor ECM
DTC	Code Description	System Response
2789-3	Drive Motor- Phase A Current Sensor: Voltage Above Normal	The Power Train will be disabled.
2789-4	Drive Motor- Phase A Current Sensor: Voltage Below Normal	Refer to FMI 4 table below.
2790-3	Drive Motor Phase B Current Sensor: Voltage Above Normal	The Power Train will be disabled.
2790-4	Drive Motor Phase B Current Sensor: Voltage Below Normal	Refer to FMI 4 table below.
2791-3	Drive Motor Phase C Current Sensor: Voltage Above Normal	The Power Train will be disabled.
2791-4	Drive Motor Phase C Current Sensor: Voltage Below Normal	Refer to FMI 4 table below.

Possible causes for an FMI 3 diagnostic code are:

• Poor connections or faulty connections in the Control Harness connectors

• The sensor circuit is shorted to a higher voltage circuit in the Control Harness.

• The current sensor has failed.

• The ECM has failed. ECM failure is unlikely.

Possible causes for an FMI 4 diagnostic code are:

• Poor connections or faulty connections in the Control Harness connectors

• The sensor signal circuit is open in the Control Harness.

• The sensor signal circuit is shorted to either frame ground or to a ground circuit in the Control Harness.

• The current sensor has failed.

• The ECM has failed. ECM failure is unlikely.

The following table lists the logic the ECM will use when low voltage conditions exist in one or more of the current sensor circuits.

Table 4

How The Motor ECM Handles FMI 4 (Low Voltage) Current Sensor Conditions
Open circuit or short to ground condition (FMI 4, low voltage)	ECM Response	Machine Operation Response
Condition exists in one the three current sensor input circuits.	The ECM detects the condition and logs a DTC for the involved sensor.	Machine continues to operate.
Condition exists in two of the three current sensor input circuits.	Due to internal limitations, the ECM will not detect that the second sensor circuit voltage is low.	Machine continues to operate for a time period. Most likely will result in a "high voltage" or "high current " Event to be activated by the Generator ECM or the Motor ECM which will disable power train operation.
Condition exists in all three of the current sensor input circuits.	The ECM will detect that all three sensor circuits are in a low voltage condition.	Power train operation will be disabled. An FMI 4 DTC will be activated for each of the three current sensors. An EID 2169 may also be triggered.

Note: As noted in the table, the ECM cannot detect that two separate current sensor circuits have a low voltage condition at the same time. Consequently, if an EID 655 (DC Power Bus Voltage High) or an EID 657, 668, 669, 670, 675, 676 (Phase Current High) is activated by the Generator ECM or the Motor ECM, the cause of the active EID could be that two current sensor circuits are in a low voltage condition. If either of these scenarios occur, check all three of the current sensor circuits for open circuits or short to ground circuit conditions to determine if two current sensor circuits have the low voltage condition.

Note: The Motor Phase Current Sensors are supplied power from the Motor ECM positive (+)15 VDC and the negative (-)15 power supplies. If the Motor ECM has activated a CID 3049 (15 V power supply) DTC or a CID 3207 (-15 V power supply) DTC, correct the problem causing these codes before performing this procedure. The Motor ECM supplies two connections for each power supply to the Power Inverter. The positive (+)15 V power supply is internally connected in each control and the negative (-)15 V power supply is internally connected in each control. Both connections for either power supplies would have to fail in order for the power to the current sensor to be interrupted.

Illustration 3	g03822626
Motor ECM current sensor connections

Note: The diagram above is a simplified schematic of the Motor ECM and the current sensor connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic, UENR4073 for the complete schematic.

Diagnostic Trouble Code Procedure

Note: Prior to beginning this procedure, inspect the harness connectors involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. If a problem with a connection is found, correct the problem and verify that the DTC is active before performing a troubleshooting procedure.

1. Identify the active FMI code associated with the components.

2. Determine which code is present and use the list below to determine which procedure to follow.

• FMI 3 DTC, proceed to Table 5.

• FMI 4 DTC code, proceed to Table 6.

Table 5

FMI 3 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Safe Shutdown Procedure This procedure must be performed before service is performed in an area that is in the vicinity of Power Train hazardous voltage components and conductors to ensure the DC power bus voltage and the Accessory Power bus voltage has discharged properly. Reference:Refer to Troubleshooting, "Electrical Maintenance Guidelines" section of this manual. Perform "Safe Shutdown Procedure for Electric Drive Tractors" before proceeding with the following troubleshooting steps.	The Safe Shutdown Procedure for Electric Drive Tractors has been performed.	OK -The Safe Shutdown Procedure for Electric Drive Tractors has been performed. The Hazardous Voltage Present Lamp and the Monitoring System Display indicate the DC system voltage has been properly discharged. The Power Train system and the Accessory Power system for the machine may now be serviced. This procedure should not require the disconnection of any of the hazardous voltage connectors. However, if an AC connection enclosure is opened or if a hazardous voltage DC connector is disconnected, a multimeter must be used to check for DC voltage between all exposed conductors and frame ground. Do not make personal contact with the exposed conductors until you have manually measured for voltage between ground and the conductors. Verify that there is less than 50.0 VDC present between all exposed AC or DC hazardous voltage conductors and frame ground before any other action is taken. Proceed to Test Step 2.
2. Check For Active DTCs A. Check for active DTCs that need to be resolved prior to troubleshooting this DTC.	The following DTCs should not be active: 3049 3207 2934 2935 2778 2779	OK -The following DTCs are not active: 3049, 3207, 2934, 2935, 2778, or 2779. This indicates other components that influence this component are functioning properly. Proceed to Test Step 3. NOT OK - There is an active DTC 3049, 3207, 2934, 2935, 2778 or 2779. Any of these may be the original cause of the DTC and must be repaired first. Repair: Refer to the Troubleshooting material for the active DTC and repair that first. After correcting that issue, operate the machine to determine if it also fixed the cause of this DTC.
3. Check The Sensor Circuits For A Short A. Turn key start switch and disconnect switch OFF. B. Disconnect the Control Harness connector from the Motor ECM and Generator ECM. Disconnect the Power Inverter harness connector. C. Inspect and clean all of the contacts of the harness connectors. Ensure that the wires and sockets are secured in the connector. Ensure that the contacts are clean, dry and in good condition. D. Examine the pins on the ECM connector which logged the DTC. Examine the pins on the Power Inverter connector. Ensure that the pins are secured in the connector and are clean, dry, and in good condition. Ensure that none of the pins are bent. E. At the Power Inverter connector, measure the resistance between the sensor signal contact and each of the other Power Inverter contacts.	Each of the resistance measurements between the sensor circuit and all of the other circuits used in the harness is greater than 5 KΩ.	OK - Each of the resistance measurements is greater than 5 KΩ. The resistance measurements indicate the current sensor circuit is not shorted to another circuit in the Control Harness. Proceed to Test Step 4. NOT OK - At least one of the resistance measurements is less than 5 KΩ. There is a short in the Control Harness. Repair: The short circuit is between the two circuits registering the low resistance measurement. There is a problem in the Control Harness. The Control Harness is a sealed harness and not serviceable. Replace the Control Harness. After the new Control Harness has been installed, ensure that the problem has been corrected before operating the machine. Proceed to Test Step 4.
4. 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 ON. C. Clear all DTCs. D. Operate the machine. E. Stop the machine and engage the parking break. F. Check if the DTC is active.	The diagnostic code is no longer present.	OK - The diagnostic code does not exist at this time. 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 previous steps a second time, the ECM may need to be flashed with the latest software. Proceed to Test Step 5.
5. Flash The Latest Software To The ECM The software program is unlikely causing this problem. However, flash the latest version of ECM software to the ECM to eliminate this condition as a possible cause. A. To flash the latest software to the Motor ECM or Generator ECM, refer to the Troubleshooting, "ECM Software - Install" procedure in this manual. After completing the flash program procedure, return to this procedure and proceed to the next step. B. After the latest version of ECM 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 DTC is active.	The FMI 3 diagnostic code is not active. No new DTCs or Event Codes have been activated.	OK: The FMI 3 diagnostic code is not active. No new DTCs or EIDs have been activated. Repair: The latest software version that has been flashed to the ECM has corrected the problem. Resume normal machine operation. STOP. NOT OK: The FMI 3 diagnostic code has been activated again by the ECM. The new software program has not corrected the problem. Proceed to Test Step 6.
6. Swap ECMs to Resolve Issue A. The Generator ECM and Motor ECM can be interchanged to aid in troubleshooting. Refer to "ECM Swap - Test" in this manual. B. Operate the machine. C. Stop the machine and engage the parking brake. D. Check if the DTC is active.	The DTC is no longer active after the ECM swap. The ECM swap resolved the issue.	OK - The DTC is no longer active. The ECM swap resolved the issue. Resume normal machine operation. NOT OK -The DTC is active on the new ECM in the original location. The problem is not related to the ECM. Repair: Clean all moisture, dirt, and corrosion from the harness. If the harness is damaged or has a short, replacement is necessary. The Control Harness is not serviceable. The Power Inverter may be the cause of the problem. If all of the above troubleshooting steps have been completed, contact the dealership Technical Communicator to consult with the Cat Dealer Solutions Network (DSN). Indicate the steps that have been taken to find the cause of the problem. The DSN will contact qualified company personnel that can make further recommendations.

Table 6

FMI 4 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Safe Shutdown Procedure This procedure must be performed before service is performed in an area that is in the vicinity of Power Train hazardous voltage components and conductors to ensure the DC power bus voltage and the Accessory Power bus voltage has discharged properly. Reference:Refer to Troubleshooting, "Electrical Maintenance Guidelines" section of this manual. Perform "Safe Shutdown Procedure for Electric Drive Tractors" before proceeding with the following troubleshooting steps.	The Safe Shutdown Procedure for Electric Drive Tractors has been performed.	OK -The Safe Shutdown Procedure for Electric Drive Tractors has been performed. The Hazardous Voltage Present Lamp and the Monitoring System Display indicate the DC system voltage has been properly discharged. The Power Train system and the Accessory Power system for the machine may now be serviced. This procedure should not require the disconnection of any of the hazardous voltage connectors. However, if an AC connection enclosure is opened or if a hazardous voltage DC connector is disconnected, a multimeter must be used to check for DC voltage between all exposed conductors and frame ground. Do not make personal contact with the exposed conductors until you have manually measured for voltage between ground and the conductors. Verify that there is less than 50.0 VDC present between all exposed AC or DC hazardous voltage conductors and frame ground before any other action is taken. Proceed to Test Step 2.
2. Check For Active DTCs A. Check for active DTCs that need to be resolved prior to troubleshooting this DTC.	The following DTCs should not be active: 3049 3207	OK -The following DTCs are not active: 3049 or 3207. This indicates other components that influence this component are functioning properly. Proceed to Test Step 3. NOT OK - There is an active DTC 3049 or 3207. Any of these may be the original cause of the DTC and must be repaired first. Repair: Refer to the Troubleshooting material for the active DTC and repair that first. After correcting that issue, operate the machine to determine if it also fixed the cause of this DTC.
3. Check The Sensor Power Supply Circuits A. Turn the disconnect switch and key start switch OFF. B. Disconnect the Power Inverter connector. C. Inspect the contacts of the Power Inverter and the harness connector. Ensure that the pins and sockets are secured in the connector and in good condition. D. Turn the disconnect switch and the key switch to the ON position. DO NOT START THE ENGINE. Note:The next two steps will measure the power supply voltage at the power supply contacts. E. At the disconnected Power Inverter connector, measure the positive power supply voltage. Use the multimeter positive probe at the positive (+)15 V contact and multimeter negative probe at the ground. F. At the disconnected Power Inverter connector, measure the negative power supply voltage. Use the multimeter negative probe at ground and use the multimeter positive probe at the negative (-)15 V contact.	The voltage measurements at both sets of the power supply connections are correct according to the diagram at the beginning of this procedure. The positive (+)15 VDC and the negative (-)15 VDC power supplies are correct.	OK - The voltage measurements are correct. The power supply is present at the assigned Power Inverter contacts. Proceed to Test Step 4. NOT OK - One or more of the voltage measurements is not correct. There is a problem with one or both of the power supplies for the current sensor. Repair: The current sensor will continue to operate if one of the positive (+)15 VDC or one of the negative (-)15 VDC power supplies is interrupted. However, both power supply circuits are required to ensure reliable machine operation. When only one of the power supply circuits is operating properly, the cause of the other faulty power supplies must be investigated and resolved at the earliest opportunity. If both of the power supply circuits for either the positive (+)15 VDC or the negative (-)15 VDC power supplies has failed, the current sensor will not operate. Check the power supply circuits again. Measure the power supply voltages to a different ECM ground connection to eliminate a bad ground circuit as the cause of an incorrect measurement. For troubleshooting the Motor or Generator ECM 15 VDC power supplies, refer to "Sensor Supply - Test" in this manual. Once the power supply problem has been corrected, verify that the FMI 4 diagnostic code is no longer active before operating the machine. STOP.
4. Check The Sensor Circuit For An Open The connector for the Power Inverter remains disconnected. A. Turn the key start switch and the disconnect switch OFF. B. Disconnect the Control Harness connector J2 from the ECM which activated the DTC. C. Inspect and clean all of the contacts of the harness connectors. Ensure that the wires and sockets are secured in the connector and the contacts are clean and in good condition. D. At the connector for the Power Inverter, connect a jumper wire between the phase current contact and the ECM ground contact. E. Measure the resistance between the ECM connector and Power Inverter connector for the current phase that logged the DTC. Verify that the jumper wire is making good contact at both of the connection points. F. While observing the multimeter resistance measurement, wiggle the Control Harness connector for the ECM which activated the DTC and the harness connector for the Power Inverter. Gently pull and move the wires around. Do not disconnect the jumper wire.	The resistance measurement is less than 5.0 Ω at all times during the manipulation of the harness and connectors.	OK - The resistance is less than 5.0 Ω. Proceed to Test Step 5. NOT OK - The resistance measurement is greater than 5.0 Ω at all times or the resistance measurement is greater than 5.0 Ω some of the time during the manipulation of the harness. Repair: The open circuit or the poor connection is in one of the sensor circuits connected by the jumper wire. The Control Harness is a sealed harness and is not serviceable. Replace the Control Harness. STOP.
5. Check The Sensor Circuit For A Short The key switch and the disconnect switch remain in the OFF position. At the Control Harness connector for the ECM which logged the DTC, attach one lead to the phase current contact that logged the DTC. Attach the other lead to the Power Inverter connector and the connector for ECM J2 which activated the code remain disconnected. A. Disconnect the Control Harness connector J2 from the OTHER ECM. B. Inspect the harness for any areas where the insulation is worn. Inspect the harness for pinch points that may cause a short circuit. C. At the Control Harness connector for the ECM that logged the DTC, attach one lead to the phase current contact that logged the DTC. Using the other lead at the connector for the Power Inverter, measure the resistance to all the contacts on that connector. Leave the lead at the ECM connector on the Control Harness and measure to the Control Harness the resistance to the support bracket.	Each of the resistance measurements is greater than 5 KΩ, except the mating contact to the contact being tested, which should be less than 5 KΩ.	OK -Each of the resistance measurements is greater than 5 KΩ, except the mating contact to the contact being tested, which should be less than 5 KΩ. The resistance measurements indicate the current sensor circuits are not shorted to another circuit or to the Control Harness support bracket in the Control Harness. Proceed to Test Step 6. NOT OK - At least one of the resistance measurements is less than 5 KΩ. There is a short in the Control Harness. Repair:The short circuit is between the current sensor signal circuit and the circuit that registered the low resistance measurement or the short circuit is between the current sensor signal circuit and frame ground. There is a problem in the Control Harness. The Control Harness is a sealed harness. This harness is not serviceable. Replace the Control Harness. After the new Control Harness has been installed, Verify the DTC no longer activates. Proceed to Test Step 6.
6. 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 ON. C. Clear all DTCs. D. Operate the machine. E. Stop the machine and engage the parking brake. F. Check if the DTC is active.	The diagnostic code is no longer present.	OK - The diagnostic code does not exist at this time. The initial diagnostic code may have been caused by a 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 previous steps a second time, the ECM may need to be flashed with the latest software. Proceed to Test Step 7.
7. Flash The Latest Software To The ECM The software program is unlikely causing this problem. However, flash the latest version of ECM software to the ECM to eliminate this condition as a possible cause. A. To flash the latest software to the Motor ECM or Generator ECM, refer to the Troubleshooting, "ECM Software - Install" procedure in this manual. After completing the flash program procedure, return to this procedure and proceed to the next step. B. After the latest version of ECM 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 DTC is active.	The FMI 4 diagnostic code is not active. No new DTCs or Event Codes have been activated.	OK: The FMI 4 diagnostic code is not active. No new DTCs or Event Codes have been activated. Repair: The latest software version flashed to the ECM has corrected the problem. Resume normal machine operation. STOP. NOT OK: The FMI 4 diagnostic code has been activated again by the ECM. The new software program has not corrected the problem. Proceed to Test Step 8.
8. Swap ECMs to Resolve Issue A. The Generator ECM and Motor ECM can be interchanged to aid in troubleshooting. Refer to "ECM Swap - Test" in this manual. B. Operate the machine. C. Stop the machine and engage the parking brake. D. Check if the DTC is active.	The DTC is no longer active after the ECM swap. The ECM swap resolved the issue.	OK - The DTC is no longer active. The ECM swap resolved the issue. Resume normal machine operation. NOT OK -The DTC is active on the new ECM in the original location. The problem is not related to the ECM. Repair: Clean all moisture, dirt, and corrosion from the harness. If the harness is damaged or has a short, replacement is necessary. The Control Harness is not serviceable. The Power Inverter may be the cause of the problem. If all of the above troubleshooting steps have been completed, contact the dealership Technical Communicator to consult with the Cat Dealer Solutions Network (DSN). Indicate the steps that have been taken to find the cause of the problem. The DSN will contact qualified company personnel that can make further recommendations.