TM 5-3805-290-23-2
ALTERNATOR REPLACEMENT - CONTINUED
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ALTERNATOR TEST
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.
2.
Turn off electrical accessories. Disconnect fuel injection pump connector (WP 0164 00). Crank the engine for 30 sec-
onds. 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.
N OT E
Cranking the engine for 30 seconds partially discharges the batteries in order to do a charging test. If the
battery has low charge, do not perform this step. Jump start engine or charge the battery before the engine
is started.
3.
Start the engine and run the engine at full throttle (TM 5-3805-290-10).
4.
Check the output current of the alternator. The initial charging current should be 13.5 A or higher with alternator at
1,500 rpm and 47 A or higher with alternator at 5,000 rpm.
5.
After approximately ten minutes of operating the engine at full throttle, the output voltage of the alternator should be
28.0 1V for a 24V system. Refer to Table 1.
6.
After ten minutes of engine operation, the charging current should decrease to approximately 10 A. The actual length of
time for the charging current to decrease to 10 A depends on the following conditions:
a.
The battery charge
b.
The ambient temperature
c.
The rpm of the engine
Refer to Table 1.
Table 1. Fault Conditions and Possible Causes.
Current at Start-up
The Voltage is Below
The Voltage is Within
The Voltage is Above
Specifications After 10
Specifications After 10
Specifications After 10
Minutes
Minutes
Minutes
Less than the specifications. Replace the alternator.
Turn on all accessories. If the
voltage decreases below the
Check the circuit of the
specifications, replace the
ignition switch.
alternator.
Decreases after matching
Replace the alternator.
The alternator and the battery Replace the alternator.
specifications.
match the specifications.
Turn on all accessories in
order to verify that the
voltage stays within
specifications.
Test the alternator again.
The alternator operates
The voltage consistently
Replace the alternator.
exceeds specifications.
within the specifications.
Inspect the battery for
Test the battery TM 9-6140- damage.
200-14.
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