TM-9-2320-361-20
2-1/2-TON, 6x6, M44A2 SERIES TRUCKS (MULTIFUEL)
TECHNICAL MANUAL; UNIT MAINTENANCE
OCTOBER 1991
TM-9-2320-361-20 - Page 181 of 1207
TM 9-2320-361-20
Table 2-4. Electrical Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Test 2. Test charging system output voltage.
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Step 8.
NOTE
Voltage regulators in both the 100 amp and 60 amp charging
systems regulate battery voltage to 28.0 ± 0.2 Vdc.
The 100 amp voltage regulator is separate from the 100 amp
alternator.
Battery voltage fluctuations are not to go above 28.5 Vdc or less
than 27.5 Vdc as headlights are turned ON, OFF, and ON with
engine running at 1200 rpm.
For test purposes only, charging voltage across batteries can be
varied between 26.0 to 30.0 Vdc with engine running at 1200 rpm
and headlights off.
Turn off engine.
Open door of battery compartment. Loosen two thumbscrews and slide batteries onto
running board.
Use multimeter to check battery for voltage.
Start engine (TM 9-2320-361-10).
Set engine speed at 1200 rpm.
Turn ON vehicle headlights and accessories.
Use multimeter to check battery voltage. Normal charging voltage on batteries is
28.0 ± 0.2 Vdc.
CAUTION
a.
b.
Do not puncture waterproof covering on cable between alternator
and voltage regulator to make voltage checks. The cable will be
unserviceable.
If battery voltage measures between 24.0 and 26.0 Vdc and alternator has no or very
weak output. Replace alternator (para. 14-50).
If battery voltage measures between 26.0 to 30.0 Vdc. adjust voltage regulator (if
equipped with adjustment screw). If charging voltage across batteries cannot be
adjusted to 28.0 ± 0.2 Vdc, replace voltage regulator (para. 14-52). If charging voltage
across batteries can be adjusted to 28.0 ± 0.2 Vdc, go to step 8.
Check voltage regulator stability.
Go to malfunction 4, test 2, step 7.
END OF TESTING!
10. BATTERIES NOT CHARGING PROPERLY (GENERATOR IN YELLOW OR RIGHT-HAND RED)
NOTE
If STE/ICE is available, perform NG50 - charging circuit tests
(chapter 2, section VII).
Test 1. Check for loose or missing alternator belts.
a. Adjust loose belts (para. 4-2).
b. Replace broken or missing belts (para. 4-2).
2-96
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