D6N Track-Type Tractor Electrohydraulic System Caterpillar

Relay - Test

Usage:

D6N GB6

Power Train ECM

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

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Table 1
Power Train ECM
DTC	Code Description	System Response
444-3	Starter Motor Relay: Voltage Above Normal	Unable to crank the engine of the machine. Starter would overheat and damage could occur.
444-5	Starter Motor Relay: Current Below Normal	Unable to crank the engine of the machine.
444-6	Starter Motor Relay: Current Above Normal	Unable to crank the engine of the machine.
3467-3	Main Power Relay: Voltage Above Normal	The voltage is outside of the acceptable range, machine will not operate. The relay would remain energized.
3467-4	Main Power Relay: Current Below Normal	The voltage is outside of the acceptable range, machine will not operate. Implements will not move. Cab blower/lights will not work. Engine may not start.
3467-5	Main Power Relay: Current Above Normal	The voltage is outside of the acceptable range, machine will not operate. Implements will not move. Cab blower/lights will not work. Engine may not start.

A relay is a component that uses a small amount of electrical current to control the state of a circuit. The circuit is either opened or closed.

Possible causes for an FMI 3 diagnostic code are:

The signal circuit is shorted to +battery.
The relay has failed.
The ECM has failed. A failure of the ECM is unlikely.

Possible causes for an FMI 5 diagnostic code are:

The supply circuit is open.
The return circuit is open.
The relay has failed.
The ECM has failed. A failure of the ECM is unlikely.

Possible causes for an FMI 6 diagnostic code are:

A short to ground exists.
The relay has failed.
The ECM has failed. A failure of the ECM is unlikely.

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Illustration 1	g03820590
Schematic of the relay circuits

Note: The diagram above is a simplified schematic of the Implement and Power Train ECM relay connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR5402, "D6N (T4F) Track-Type Tractor Electrical System" for the complete schematic.

Diagnostic Trouble Code Procedure

Note: Prior to beginning this procedure, inspect the harness connectors that are 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. Check the wiring harness 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 the 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 3 diagnostic code, proceed to Table 2.
FMI 5 diagnostic code, proceed to Table 3.
FMI 6 diagnostic code, proceed to Table 4.

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Table 2
FMI 3 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Check The Machine Harness For A Short A. Turn the key start switch and disconnect switch OFF. B. Disconnect the relay from the harness. C. Disconnect the ECM machine harness connectors. D. At the ECM machine harness connector, measure the resistance between the signal contact and all other contacts that are used in the ECM.	Each resistance measurement is greater than 5KΩ.	OK - All resistance measurements are greater than 5K Ω. Proceed to Test Step 2. NOT OK - One or more readings are less than 5 Ω. Repair: A short exists between the signal contact and the circuit with the low resistance. 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 2.
2. 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 diagnostic codes. D. Operate the machine. E. Stop the machine and engage the safety lock. F. Check if the diagnostic code 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 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.

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Table 3
FMI 5 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Check The Relay A. Turn the key start switch and disconnect switch OFF. B. Disconnect the relay from the wiring harness. C. At the machine harness connector for the relay, place a jumper wire between the signal wire and the signal return. D. Turn the key start switch and the disconnect switch ON. Do not start the engine. E. Observe the status of the diagnostic code.	The diagnostic code changes from anFMI 5 to an FMI 6 after the jumper wire is installed.	OK - The harness is correct. The diagnostic code changes from an FMI 5 to an FMI 6 after the jumper wire is installed. The relay has failed. Repair - Replace the relay. Proceed to Test Step 3. NOT OK - The diagnostic code remains active. Proceed to Test Step 2.
2. Check The Harness For An Open A. Turn key start switch and disconnect switch OFF. B. Disconnect the machine harness connectors from the ECM. C. The jumper wire remains installed. D. At the ECM machine harness connector, measure the resistance between the signal contact and the return contact.	The resistance is less than 5 Ω.	OK - The resistance is less than 5Ω. The machine harness is correct. Proceed to Test Step 3. NOT OK - The resistance is greater than 5 Ω. The resistance measurement is not correct. There is an open circuit in the machine harness. Repair: 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 3.
3. 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 diagnostic codes. D. Operate the machine. E. Stop the machine and engage the safety lock. F. Check if the diagnostic code 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 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.

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Table 4
FMI 6 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Check The Relay A. Turn the key start switch and disconnect switch ON. B. Observe the status of the diagnostic code. C. Disconnect the relay from the machine harness.	The FMI 6 changes to FMI 5 when the relay is disconnected.	OK - FMI 6 changes to FMI 5 when the relay is disconnected. The harness is correct. The relay has failed. Repair: Repair or replace the relay. Proceed to Test Step 3. NOT OK - The diagnostic code remains active. Proceed to Test Step 2.
2. Check The Return Circuit For A Short To Ground A. Turn key switch and disconnect switch OFF. B. The relay remains disconnected from the machine harness. C. Disconnect the machine harness connectors from the ECM. D. At the ECM machine harness connector, measure the resistance between the signal contact and all other contacts that are used in the ECM.	Each resistance measurement is greater than 5K Ω.	OK - Each resistance measurement is greater than 5K Ω. The machine harness is correct. Proceed to Test Step 3. NOT OK - Each resistance measurement is not greater than 5K Ω. A short circuit exists between the signal circuit and the circuit with the low resistance measurement. Repair: 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 3.
3. 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 diagnostic codes. D. Operate the machine. E. Stop the machine and engage the safety lock. F. Check if the diagnostic code 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 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.