538, 548 and 558 Forest Machine Sensor Supply

Sensor Supply - Test

538, 548 and 558 Forest Machine [M0066266]

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ELECTRICAL AND STARTING SYSTEM

SENSOR GP

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538, 548 and 558 Forest Machine Sensor Signal (Analog, Passive) - Test

538, 548 and 558 Forest Machine Sensor Supply - Test

1.1. Machine ECM

2.1. Diagnostic Trouble Code Procedure

Machine ECM

The following is a list of Diagnostic Trouble Codes (DTC) that are associated with the sensor power supply circuits of the machine.

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Table 1
Machine ECM (MID 299)
DTC	Code Description	System Response
41-3	8 V Supply : Voltage Above Normal	Multiple failures of systems or components associated with this code.
41-4	8 V Supply : Voltage Below Normal	Multiple failures of systems or components associated with this code.
41-6	8 V Supply : Current Above Normal	Multiple failures of systems or components associated with this code.

The diagnostic code is recorded when the interface module indicates that the current of the sensor supply circuit is too high.

Possible causes of an FMI 3 diagnostic code are:

The sensor supply or the ground circuit in the machine harness is open.
The signal circuit in the machine is shorted to another circuit.
The signal circuit In the machine harness is open or the sensor is disconnected.
The sensor has failed.
The ECM has failed. A failure of the ECM is unlikely.

Possible causes of an FMI 4 diagnostic code are:

The signal circuit in the machine harness is shorted to ground.
The sensor has failed.
The ECM has failed. A failure of the ECM is unlikely.

Possible causes of an FMI 6 diagnostic code are:

The sensor supply output is shorted to ground.
A sensor in the power supply circuit has failed.
The ECM has failed. A failure of the ECM is unlikely.

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Illustration 1	g06026729
Schematic of the Sensor Supply circuits

The preceding diagram is a simplified schematic of the sensor supply 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 machine circuitry.

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. If a problem with a connection is found, correct the problem and verify that the diagnostic code is active before performing a troubleshooting procedure. For sensors powered via the fuse panel, check the condition of the appropriate fuse before beginning the troubleshooting procedure.

Identify the active FMI code associated with the components.
Determine the active failure mode code and use the list below to determine which procedure to follow.
- FMI 3 diagnostic code, proceed to Table 2
- FMI 4 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 Supply Voltage At The Sensor A. Turn the disconnect switch and the key start switch to the ON position. B. Do not disconnect the sensor from the machine harness. C. Refer to the schematic to determine the voltage source for the suspected faulty sensor. D. At the back of the contact for the sensor, insert the multimeter probes along the supply contact and the return contact. Measure the voltage.	The voltage is correct for the appropriate sensor supply.	OK - The sensor supply voltage is correct. Proceed to Test Step 2. NOT OK - The sensor supply voltage is not correct. Proceed to Test Step 4.
2. Check For Proper Ground At The Sensor A. The machine harness remains connected to the sensor. B. Turn the disconnect switch and the key start switch to the OFF position. C. Remove the multimeter probe from the voltage supply wire. D. At the back of the harness connector for the sensor, insert a multimeter probe along the ground wire contact. E. Measure the resistance from the ground contact to frame ground.	The resistance is less than 5 &OHacgr;.	OK - The resistance is less than 5 &OHacgr;. The ground circuit is correct. Proceed to Test Step 3. NOT OK - The resistance is greater than 5 &OHacgr;. The ground circuit in the machine harness has failed. Repair: Replace or repair the machine harness. Proceed to Test Step 4.
3. Check For A Short To Battery A. Turn the key start switch and the disconnect switch to the ON position. B. Disconnect the machine harness from the ECM. C. At the ECM harness connector fro the ECM, measure the voltage from the sensor supply contact to frame ground.	The voltage is 0.0 ± 0.5 V.	OK - The voltage is 0.0 ± 0.5 V. The voltage is correct. The ECM may have failed. Proceed to Test Step 4. NOT OK - The voltage is NOT 0.0 ± 0.5 V. The machine harness has failed. 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. Repair: Repair or replace the machine harness. 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 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 4 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Check The Sensor A. With FMI 4 active, disconnect the sensor from the machine harness. B. Observe Cat ^® ET or the operator monitor for a code change as the sensor is disconnected and connected to the harness.	The code is observed changing from FMI 4 to FMI 3.	OK - The diagnostic code changed to FMI 3 when the sensor was disconnected. Repair: Replace the sensor. Proceed to Test Step 4. NOT OK - The FMI 4 diagnostic code remains active when the sensor is disconnected. The sensor is not the cause of the problem. Proceed to Test Step 2.
2. Check The Signal Circuit For A Short To Ground A. The disconnect switch and the key start switch remain in the OFF position. B. The sensor remains disconnected from the harness. C. Disconnect the J1 and J2 connector from the ECM. D. Measure the resistance between the signal contact for the sensor and frame ground.	The resistance is greater than 5 K&OHacgr;.	OK - The resistance is greater than 5K &OHacgr;. The harness circuit is correct. Proceed to Test Step 3. NOT OK - The resistance is less than 5 &OHacgr;. A short circuit exists between frame ground and the signal circuit. 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. Repair: Repair or replace the machine harness. Proceed to Test Step 4.
3. Check The Supply Voltage At The Sensor A. Turn the key start switch and the disconnect switch to the ON position. B. Disconnect the machine harness from the sensor. C. Refer to the schematic to determine the voltage source for the suspected faulty sensor. D. Measure the voltage between signal and ground contacts at the machine harness connector for the sensor.	The voltage is correct for the sensor being supplied.	OK - The voltage reading is correct for the suspected faulty sensor. Proceed to Test Step 4. NOT OK - The voltage is not within the expected range for the circuit. 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. Repair: Repair or replace the machine harness. 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 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 4
FMI 6 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Check The Voltage At The ECM A. Turn the disconnect switch and the key start switch to the ON position. B. Check the voltage at the connector of the ECM between the sensor supply contact and the ground contact. Use the 7X-1710 Cable Probes to measure this voltage. Do NOT disconnect the machine harness from the ECM. Use the illustration above to determine the correct voltage.	The voltage is correct for the appropriate sensor supply.	OK - The sensor supply voltage is correct. Proceed to Test Step 2. NOT OK - The sensor supply voltage is not correct. Proceed to Test Step 4.
2. Check The Sensors A. The disconnect switch and the key start switch remain in the ON position. B. Observe the status of the diagnostic code, and disconnect each sensor from the applicable illustration above.	The diagnostic code is no longer active when one of the sensors in the supply circuit is disconnected	OK - The diagnostic code is not active when one of the sensors in the supply circuit is disconnected. The power supply circuit is correct. Repair: Repeat this test step to determine the sensor that causes the problem. Replace the sensor that is causing the problem. Proceed to Test Step 4. NOT OK - The diagnostic code is still active. Disconnecting the components in the circuit did not change the status of the diagnostic code. Proceed to Test Step 3.
3. Check For A Short To Ground A. Turn the key start switch and the disconnect switch to the OFF position. B. Disconnect the machine harness connectors from the ECM. C. At the ECM harness connector, measure the resistance between frame ground and the contact for the sensor supply.	The resistance is greater than 5K Ω.	OK - The resistance is greater than 5K Ω. The harness circuit resistance is correct. Verify that the diagnostic code is present. Proceed to Test Step 4. NOT OK - The resistance is less than 5 Ω. The machine harness has failed. 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. Repair: Repair or replace the machine harness. 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 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