259D Compact Track Loader – Alternator – Test

Table 1
Required Tools    
Part Number     Part Name     Qty    
6V-7070     Digital Multimeter     1    
8T-0900     Ammeter     1    

  1. Put the positive lead "+" of the multimeter on the "Bat" terminal of the alternator. Put the negative "-" lead on the ground terminal or on the frame of the alternator. Put the ammeter around the positive output wire of the alternator.

  1. Turn off all electrical accessories. Turn off the fuel to the engine. Crank the engine for 30 seconds. Wait for two minutes in order to cool the starting motor. If the electrical system appears to operate correctly, crank the engine again for 30 seconds.

    Note: Cranking the engine for 30 seconds partially discharges the batteries in order to do a charging test. If the battery has a low charge, do not perform this step. Jump start the engine or charge the battery before the engine is started.

  1. Start the engine and run the engine at full throttle.

  1. Check the output current of the alternator. The initial charging current should be equal to the minimum full load current or greater than the minimum full load current. Refer to Specifications, "Alternator and Regulator" for the correct minimum full load current.

    Table 2
    Fault Conditions And Possible Causes    
    Current At Start-up     The Voltage Is Below Specifications After 10 Minutes.     The Voltage Is Within Specifications After 10 Minutes.     The Voltage Is Above Specifications After 10 Minutes.    
    Less than the specifications     Replace the alternator. Check the circuit of the ignition switch.     Turn on all accessories. If the voltage decreases below the specifications, replace the alternator.     -    
    Decreases after matching specifications     Replace the alternator.     The alternator and the battery match the specifications. Turn on all accessories in order to verify that the voltage stays within specifications.     Replace the alternator.    
    The voltage consistently exceeds specifications.     Follow the procedures that are in the Tool Operating Manual, SEHS7633 in order to test the battery. Test the alternator again.     The alternator operates within the specifications. Follow the procedures in the Tool Operating Manual, SEHS7633 in order to test the battery.     Replace the alternator. Inspect the battery for damage.    

  1. After approximately ten minutes of operating the engine at full throttle, the output voltage of the alternator should be 14.0 ± 0.5 volts for a 12 volt system. After approximately ten minutes of operating the engine at full throttle, the output voltage of the alternator should be 28.0 ± 1 volts for a 24 volt system. Refer to the Fault Conditions And Possible Causes in Table 2.

  1. After ten minutes of engine operation, the charging current should decrease to approximately 10 amperes. The actual length of time for the charging current to decrease to 10 amperes depends on the following conditions:

    • The battery charge

    • The ambient temperature

    • The rpm of the engine

    Refer to the Fault Conditions And Possible Causes in Table 2.

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