NUT 2941867 - Caterpillar

Illustration 5 g03605378
Schematic of the Electrical Power SupplyNote: The diagram above is a simplified schematic of the Implement ECM 3 and the Electrical Power Supply connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR3921 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. Check the wiring 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 this diagnostic code is active before performing a troubleshooting procedure.
Table 6
Troubleshooting Test Steps    Values    Results    
1. Identify Active FMI Code Associated With The System Voltage Circuit    
Code present.     FMI 2 diagnostic code, proceed to Test Step 2.
FMI 3 diagnostic code, proceed to Test Step 7.
FMI 4 diagnostic code, proceed to Test Step 8.    
Begin Process For FMI 2 Troubleshooting HERE    
2. Check The Supply Circuits
A. Turn the disconnect switch and the key start switch to the OFF position.
B. Disconnect the harness connector from the ECM.
C. At the harness connector for the ECM, measure the resistance between the supply voltage to each of the positive contacts of the battery.
D. At the harness connector for the ECM, measure the resistance between the supply voltage to the keyswitch contact.    
Each resistance is less than 5 Ω.     OK - Each resistance is less than 5 Ω.
Repair: Reconnect the harness connector to the ECM.
Proceed to Test Step 3.
NOT OK - A resistance is greater than 5 Ω. There is an open or poor connection in the supply circuit.
Repair: Inspect the harness. Perform a
45 N (10 lb) pull test on each circuit wire. Reconnect all connectors. Check for intermittent problems usingCaterpillar® Electronic Technician (Cat® ET).
Proceed to Test Step 10.    
3. Check The Ground Circuits
A. Turn the disconnect switch and the key start switch to the OFF position.
B. Disconnect the harness connector from the ECM.
C. At the harness connector for the ECM, measure the resistance between each of the negative battery contacts and frame ground.    
Each resistance is less than 5 Ω.     OK - Each resistance is less than 5 Ω.
Proceed to Test Step 4.
NOT OK - A resistance is greater than 5 Ω. The harness has failed.
Repair : Repair or replace the harness.
Proceed to Test Step 10.    
4. Check The Current Output Of The Alternator
A. Partially discharge the batteries.
B. Turn the disconnect switch and the key start switch to the OFF position.
C. Connect one multimeter probe to the R terminal of the alternator.
D. Connect the other multimeter probe to the frame ground.
E. Connect a clamp on an ammeter around the output wire .
F. Turn ONthe disconnect switch.
G. Start the engine.
H.