SHAFT-PLNTY-YM 2151875 - Caterpillar

Probable Causes
Alternator
Charging CircuitRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
Troubleshooting Test Steps Values Results
1. Condition of the Alternator Drive Belts
A. Inspect the condition of the alternator drive belts.
B. Check the belt tension. If the engine is equipped with an automatic belt tensioner, check the automatic belt tensioner.
Excessive belt tension can result in damage to the alternator.
Drive belt
Result: The alternator drive belts are in good condition and the belt tension is correct.
Proceed to Test Step 2.
Result: The alternator drive belts are not in good condition or the belt tension is incorrect.
If the alternator drive belts are worn or damaged, replace the belts. Refer to Disassembly and Assembly for the correct procedure.
If necessary, replace the automatic belt tensioner. Refer to Disassembly and Assembly for the correct procedure.
2. Condition of the Alternator Drive Pulley
A. Check the condition of the alternator drive pulley. Look for deep grooves that have been worn into the pulley by the belt. Check that the nut for the pulley has not become loose.
Alternator Drive Pulley
Result: There is excessive wear on the alternator drive pulley.
Replace the pulley.
Result: The alternator drive pulley nut was loose.
Tighten the nut.
Result: There is not excessive wear on the alternator drive pulley.
Proceed to Test Step 3.
3. Wear of the Alternator Bearings
A. Check the alternator bearings for signs of wear.
Alternator bearings
Result: The alternator bearings are OK.
Proceed to Test Step 4.
Result: The alternator bearings are not OK.
Repair the alternator or replace the alternator, as needed. Refer to Disassembly and Assembly for the correct procedure.
4. Operation of the Alternator or Regulator
A. Verify that the alternator or the regulator is operating correctly. Refer to Special Instruction, REHS0354, "Charging System Troubleshooting" for the proper testing procedures.
Regulator and alternator
Result: The regulator and alternator are operating properly.
Proceed to Test Step 5.
Result: The regulator and alternator are not operating properly.
Repair the alternator and regulator or replace the alternator and regulator, as needed. Refer to Disassembly and Assembly for the correct procedure.
5. Inspection of the Charging Circuit
A. Inspect the battery cables, wiring, and connections in the charging circuit.
Charging circuit
Result: The charging circuit is not working properly.
Clean all connections and tighten all connections. Replace any faulty parts.
Complete the procedure in the order in which the steps are listed.