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 364 of 1275

TM 9-2350-311-20-1

3-3 TROUBLESHOOTING CHART — CONTINUED

v. B.O. MARKERS AND B.O. DRIVE LIGHTS

(3) B.O. DRIVE LIGHT FAILS TO OPERATE; ALL

CIRCUIT — CONTINUED

OTHER LIGHTS OPERATE — CONTINUED

CONTINUED FROM STEP A

1. Reconnect bulkhead-to-driver’s instrument

panel wiring harness to main light switch.

2. Remove reflector and B.O. drive light bulb

(para 8-22).

3. Place red lead of multimeters in center contact

and black lead to ground.

4. Turn MASTER switch ON, place main light

switch to B.O. DRIVE position, and check for

voltage.

5. Turn MASTER and main light switches OFF.

Is voltage present?

C

1. Install reflector and B.O. drive light bulb

(para 8-22).

2. Remove headlight assembly (para 8-23).

3. Place red lead of multimeters in socket G (lead

19) and black lead to ground.

4. Turn MASTER switch ON, place main light

switch to B.O. DRIVE position, and check for

voltage.

5. Turn MASTER and main light switches OFF.

I

Is voltage present?

CONTINUED ON NEXT PAGE

3-264

Replace B.O. drive light bulb

(para 8-22).

Replace lead 19 of headlight

wiring harness (para 8-48).