538, 548 and 558 Forest Machine Relay

Relay - Test

538, 548 and 558 Forest Machine [M0066266]

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ELECTRICAL AND STARTING SYSTEM

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1.1. Machine ECM

2.1. Diagnostic Trouble Code Procedure

Machine ECM

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

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Table 1
Machine ECM (MID 299)
DTC	Code Description	System Response
781-3	Lighting Relay: Voltage Above Normal	Related lighting system will be ON continuously.
781-6	Lighting Relay: Current Above Normal	Related lighting system will be ON continuously.
2912-3	Front Wiper Speed Control Relay: Voltage Above Normal	Wiper system will not function.
2912-6	Front Wiper Speed Control Relay: Current Above Normal	Wiper system will not function.
3634-3	Boom Light Relay: Voltage Above Normal	Related lighting system will be ON continuously.
3634-6	Boom Light Relay: Current Above Normal	Related lighting system will be ON continuously.

A relay is a component that uses a small amount of electrical current to control a large amount of electrical current.

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 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	g06026931
Schematic of the relay circuits.

The preceding diagram is a simplified schematic of the relay connections. The schematic is electrically correct. However, not all the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic to view the entire circuitry of the machine.

Diagnostic Trouble Code Procedure

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. 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 6 diagnostic code, proceed to Table 3.

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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 to the OFF position. 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 used in the ECM.	Each resistance measurement is greater than 5Ω.	OK - All resistance measurements are greater than 5 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 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 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 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 AVSpare. 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 6 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Check The Relay A. Turn the key start switch and disconnect switch to the ON position. B. Observe the status of the diagnostic code. C. Disconnect the relay from the machine harness.	FMI 6 is no longer active when the relay is disconnected.	OK - FMI 6 is no longer active 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 to the OFF position. 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 5 Ω.	OK - Each resistance measurement is greater than 5 Ω. The machine harness is correct. Proceed to Test Step 3. NOT OK - Each resistance measurement is not greater than 5 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 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 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 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 AVSpare. This consultation may effect repair time. Follow the steps in Troubleshooting, "ECM - Replace" if the ECM needs to be replaced. STOP