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