NUT 1952221 - Caterpillar

Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections may 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.The FMI 2 error code will only be logged under the following conditions:
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.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.Possible causes for an FMI 6 Diagnostic code are:
A wire is shorted to ground.
The charging system component has failed.
The ECM has failed. A failure of the ECM is unlikely.
Illustration 1 g06248897
Implement Electrical Power Supply Connections for Machine
Note: The diagram above is a simplified schematic of the electrical circuit. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic 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. 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.
Table 3
Troubleshooting Test Steps Values Results
1. Identify Active FMI Code Associated With The System Voltage Circuit. Code present.
FMI 5 diagnostic code, proceed to Test Step 2.
FMI 6 diagnostic code, proceed to Test Step 4.
Begin Process For FMI 5 Troubleshooting Here
2. Check For An Open Circuit
A. Turn key start switch and disconnect switch OFF.
B. Disconnect the wire at alternator terminal labeled "W".
C. Disconnect the same wire from the Switch Panel (refer to Illustration ).
D. Connect one end of the wire to a known good ground.
E. 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 five KΩ. The wire in the harness between the alternator and the Switch Panel is open or damaged.
Repair- Repair or replace the wiring harness.
Note: A resistance that is greater than five Ω but less than five KΩ would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than five KΩ would indicate an open in the circuit.
Proceed to Test Step