349F and 352F Excavator Machine System Caterpillar

Sensor Supply - Test

Usage:

Machine ECM

The following is a list of Diagnostic Trouble Codes (DTCs) 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 VDC Supply: Voltage Above Normal	Multiple failures of systems or components associated with this code.
41-4	8 VDC Supply: Voltage Below Normal	Multiple failures of systems or components associated with this code.
262-3	5 VDC Sensor Power Supply: Voltage Above Normal	Multiple failures of systems or components associated with this code.
262-4	5 VDC Sensor Power Supply: Voltage Below Normal	Multiple failures of systems or components associated with this code.

The sensor supply is the voltage output originating from the electronic control module connections.

Possible causes of an FMI 3 diagnostic code are:

The sensor supply is shorted to +battery.
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.
A sensor has failed.
The ECM has failed. A failure of the ECM is unlikely.

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Illustration 1	g06112609
Machine ECM J1 Sensor Supply connections

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Illustration 2	g06118531
Machine ECM J2 Sensor Supply connections

The preceding diagrams are simplified schematics of the machine ECM connections. The schematics are 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.

Implement Control ECM

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

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Table 2
Implement Control ECM (MID 272)
DTC	Code Description	System Response
41-3	8 VDC Supply: Voltage Above Normal	Multiple failures of systems or components associated with this code.
41-4	8 VDC Supply: Voltage Below Normal	Multiple failures of systems or components associated with this code.
262-3	5 VDC Sensor Power Supply: Voltage Above Normal	Multiple failures of systems or components associated with this code.
262-4	5 VDC Sensor Power Supply: Voltage Below Normal	Multiple failures of systems or components associated with this code.

The sensor supply is the voltage output originating from the electronic control module connections.

Possible causes of an FMI 3 diagnostic code are:

The sensor supply is shorted to +battery.
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.
A sensor has failed.
The ECM has failed. A failure of the ECM is unlikely.

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Illustration 3	g06113181
Implement Control ECM Sensor Supply connections

The preceding diagram is a simplified schematic of the implement control ECM connections. The schematics 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 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. 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 which code is present and use the list below to determine which procedure to follow.

FMI 3 diagnostic code, proceed to Table 3.
FMI 4 diagnostic code, proceed to Table 4.

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Table 3
FMI 3 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Check The Voltage At The Sensors A. Turn key start switch and disconnect switch ON. B. Disconnect the machine harness connector for the sensors. C. At the machine harness connector for the sensors, measure the voltage between the sensor supply contact and the sensor return contact.	Voltage reading is correct for the sensors.	OK - The voltage reading is correct for the sensors. Proceed to Test Step 4. NOT OK - The voltage is greater than the supply for the circuit. Proceed to Test Step 2.
2. Check The Power Supply At The ECM A. Turn the key start switch and disconnect switch to the OFF position. B. At the J1 harness connector for the ECM, use a 151-6320 Removal Tool to remove the supply wire and the sensor return wire. The harness connector remains connected to the ECM. C. Turn the disconnect switch and the key start switch to the ON position. D. Use the multimeter probes in order to make contact on the connector pins. Measure the voltage at the ECM pins between the sensor supply contact and sensor return contact .	Voltage reading is correct for the supply.	OK - The voltage is correct. The ECM power supply is correct. Install the wires and sockets that were removed from the ECM connector back into the original locations. Proceed to Test Step 3. NOT OK - The voltage measurement is greater than the supply voltage. The measurement is not correct. The ECM may have failed. Proceed to Test Step 4.
3. Check For A Short In the Harness A. The sensors remain disconnected from the machine harness. B. The key start switch and disconnect switch remainOFF. C. Disconnect the machine harness connectors from the ECM. D. At the ECM harness connector, measure the resistance between the supply contact and all of the other contacts that are used for the ECM.	Each resistance is greater than 5K Ω.	OK - Each resistance is greater than 5K Ω. Proceed to Test Step 4. NOT OK - One or more readings less than 5 Ω. There is a short between the signal contact and the circuit with the low resistance. Repair: Refer to the complete electrical schematic. Examine all of the connectors of the machine harness for possible short circuits. 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 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 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 4 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Check The Sensors A. Turn the key start switch and disconnect switch to the ON position. B. Observe the status of the diagnostic code as each sensor is disconnected.	The FMI 4 diagnostic code is no longer active when one of the sensors on 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 in order 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 sensors in the circuit did not affect the status of the diagnostic code. Proceed to Test Step 2.
2. Check The Signal Circuit For A Short To Ground A. Turn the key start switch and the disconnect switch OFF. B. Disconnect the harness connectors from the ECM. C. Measure the resistance between the power supply contact and frame ground. D. Measure the resistance between the power supply contact and all of the other contacts that are used for the ECM.	Each resistance is greater than 5K Ω.	OK - Each resistance is greater than 5K Ω. The harness circuit is correct. Proceed to Test Step 3. NOT OK - The resistance is less than 5 Ω. The power supply circuit is shorted to ground. The short circuit exists between the power supply circuit and the circuit with the low resistance measurement. Repair: Repair or replace the machine harness. Proceed to Test Step 4.
3. Check The Power Supply At The ECM A. Turn the key start switch and disconnect switch to the OFF position. B. At the J1 harness connector for the ECM, use a 151-6320 Removal Tool to remove the supply wire and the sensor return wire. The harness connector remains connected to the ECM. C. Turn the disconnect switch and the key start switch to the ON position. D. Use the multimeter probes in order to make contact on the connector pins. Measure the voltage at the ECM pins between the sensor supply contact and sensor return contact .	Voltage reading is correct for the supply.	OK - The voltage is correct. The ECM power supply is correct. Install the wires and sockets that were removed from the ECM connector back into the original locations. Proceed to Test Step 4. NOT OK - The voltage measurement is less than the supply voltage. The measurement is not correct. The ECM has failed. 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 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.