TM-9-2350-311-20-1

HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5

TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR HULL, POWERPLANT, DRIVE CONTROLS, TRACKS, SUSPENSION, AND ASSOCIATED COMPONENTS

AUGUST 1994

TM-9-2350-311-20-1 - Page 277 of 1275

TM 9-2350-311-20-1

CONTINUED FROM STEP J

2.

3.

4.

5.

6.

7.

8.

9.

10.

1 .

Reconnect rectifier-to-voltage regulator

wiring harness to rectifier,

Disconnect battery ground leads.

Disconnect rectifier-to-voltage regulator

wiring harness from voltage regulator.

Place jumper wires from pin E (lead 3) to a

battery negative terminal and pin B (lead 1 ) to

the positive terminal of same battery.

Disconnect lead 2A from battery positive

terminal.

Reconnect battery ground leads.

Turn MASTER switch ON and run vehicle

engine at idle speed (750 rpm).

Set multimeter on dc scale and place red lead

of multimeter on lead 2A and black lead

to ground.

Check for voltage.

Turn MASTER switch and engine OFF.

Is voltage above 27.5 Vdc?

Repair or replace rectifier-to-voltage

regulator wrong harness (para 8-60).

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 27 B).

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.

CONTINUED ON NEXT PAGE

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