303.5E2 CR Mini-HEX Machine ECM Caterpillar

Electrical Power Supply - Test

Usage:

Machine ECM

The following Diagnostic Trouble Code (DTC) is associated with the system voltage circuit of the machine. The ECM engages the code when a drop in electrical current to the control module is detected.

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Table 1
Machine ECM (MID 39)
DTC	Code Description	System Response
E0875 and/or 168-5	Electrical System Voltage : Current Below Normal	Numerous machine system failures can be expected when this code is active.

Possible Causes for an FMI 5 diagnostic code are:

A charging system component has failed.
The machine harness is open.
The ECM has failed. A failure of the ECM is unlikely.

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Illustration 1	g06037535
Illustration of the Machine ECM electrical system connections.

The preceding diagram is a simplified schematic of the electrical circuit connections for machine power. The schematic is electrically correct. However, not all the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR6662 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. Disconnect the harness connectors. Check the inside of the connectors for signs of moisture, rust, or damage to the pins of the connector. 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. This inspection is especially useful if an intermittent problem is suspected.

Refer to Table 2 for FMI 5 troubleshooting instructions.

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Table 2
FMI 5 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Check For An Open Circuit A. Turn key start switch and disconnect switch to the OFF position. B. Disconnect the wire at alternator terminal labeled “IG”. C. Connect one end of the wire to a know good ground. D. Measure the resistance of the wire at the open end of the connector.	The resistance is 5 Ω or less.	OK - The machine harness appears to work correctly. Either the alternator is not working correctly or the ECM may be recording the diagnostic code incorrectly. Proceed to Test Step 2. NOT OK - The resistance measurement is greater than 5K Ω. The wire in the harness between the alternator and the dependent components is open or damaged. Repair: Repair or replace the wiring 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 4.
2. Check The Charging System At High Idle A. Turn key start switch and disconnect switch to the ON position. B. Clear all active diagnostic codes. C. Start the engine. Run engine at HIGH idle. D. Enter the diagnostic menu on the monitor. E. Observe status of diagnostic code.	Diagnostic code is no longer active.	OK - Diagnostic code is no longer active. Proceed to Test Step 3. NOT OK - Diagnostic code remains active. Repair : A charging system component may be faulty. Check the charging system. Special Instruction, REHS0354, "Charging System Troubleshooting" for more information. Proceed to Test Step 4.
3. Check The Charging System At Low Idle A. Turn key start switch and disconnect switch to the ON position. B. Clear all active diagnostic codes. C. Start the engine. Run the engine at LOW idle. D. Enter the diagnostic menu on the monitor. E. Observe status of diagnostic code.	Diagnostic code is no longer active.	OK - The diagnostic code is no longer active. Proceed to Test Step 4. NOT OK - The diagnostic code is active. The charging system is not charging at the proper output. Repair : A charging system component may be faulty. Check the charging system. Special Instruction, REHS0354, "Charging System Troubleshooting" for more information. 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 Caterpillar. This consultation may effect repair time. Follow the steps in Troubleshooting, "ECM - Replace" if the ECM needs to be replaced. STOP.