ROD 4175760 - Caterpillar

Table 1
Required Tools
Part Number Part Name Qty
6V-7070 Digital Multimeter 1
8T-0900 Ammeter 1
Draw down the battery below 12.4 V by turning on the lights or other loads for approximately 5 minutes. Start the machine.
Check amperage of alternator cable. This will vary based on functions turned on in the cab. The amperage should be approximately 20-40 amps.Note: As battery charge increases, alternator amperage output will decrease.
Check voltage at Battery+ post. After 10 minutes of operation, the voltage should be 14 V 0.5 V. If within the specification, then the alternator is good. If not within 14 V 0.5 V, then go to the next step to troubleshoot the entire circuit prior to replacing the alternator.
Inspect the condition of the alternator belts and check that the belt tension is within specification. Refer to the machine Operation Maintenance Manual for proper belt tension. Make any necessary repairs and then repeat Step 3.
Check the condition of the alternator drive pulley and alternator bearing. Make any necessary repairs and then repeat Step 3.
Inspect the battery cables, engine ground, and wiring. Clean and/or wire brush connections as needed. Make any necessary repairs and then repeat Step 3.
With ignition in the ON position, verify that the signal wire on the alternator has 12 V by touching the positive lead of the multimeter to the wire terminal and the negative lead to any frame ground. If it does not have approximately 12 V, then troubleshoot the wiring from the fuse block to the alternator. Make any necessary repairs and then repeat Step 3.Note: The alternator signal wires are below:
Skid Steer Loader, Multi-Terrain Loader, and Compact Track Loader are 123-WH
Compact Wheel Loader is 111-YL
Mini Hydraulic Excavator is 123-WH