TM-9-2350-311-20-1 Maintenance Manual for Volume 1 M109 Hull Download
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TM 9-2350-311-20-1 3-3 TROUBLESHOOTING CHART — CONTINUED m. ALTERNATOR CIRCUIT (M109A2/M109A3)— ALTERNATOR FAILS TO CHARGE BATTERIES; GAGE CONTINUED INDICATION: NOT CHARGING, UNSTEADY OR INACCURATE READING — CONTINUED CONTINUED FROM STEP K NOTE • Batteries can be totally discharged within 4 to 6 hours if air cleaner blower motor system is malfunctioning or if blower motors operate full time. Troubleshooting step L provides a basic test of blower motor circuit by testing blower motor relay output voltage to voltage regulator (lead 27B). • If blower motor relay output is 24 Vdc or greater (battery power) with voltage regulator disconnected from circuit, voltage regulator is malfunctioning/inoperative and will not charge battery. • If voltage is less than 24 Vdc (battery power), blower motor circuit is malfunctioning and discharging battery. I L 1. Reconnect rectifier to voltage regulator wiring harness to voltage regulator. 2. Disconnect battery ground leads. 3. Disconnect engine disconnect bracket-to- bulkhead wiring harness from voltage regulator. 4. Place jumper wires from socket A (lead 2) to socket B (lead 400-459B), from pin C (lead 3) to battery negative terminal, and from pin F (lead 27B) to positive terminal of same battery to apply 12 Vdc to alternator field. 5. Reconnect battery ground leads. 6. Turn MASTER switch ON and run vehicle engine at 1000 rpm (oil pressure at 12 psi [83 kPa]). 7. Place red lead of multimeters in socket F (lead 27B) and black lead to ground. 8. Check for voltage. Is voltage above 27.5 Vdc? I CONTINUED ON NEXT PAGE 3-164