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 358 of 1275

TM 9-2350-311-20-1

3-3 TROUBLESHOOTING CHART —

CONTINUED

v.

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

CIRCUIT — CONTINUED

(1) FRONT B.O. MARKER LIGHTS FAIL TO

OPERATE; ALL OTHER LIGHTS OPERATE

Tools

General mechanic’s tool kit (item 64, Appx H)

Driver’s instrument panel released (para 8-17)

Multimeters (item 36, Appx H)

TA-1 Probe kit (item 43, Appx H)

A

1. Disconnect bulkhead-to-driver’s instrument

2.

3.

4.

panel wiring harness from main light switch.

Place a jumper wire from socket F (lead

15) to socket E (lead 20/24).

Turn MASTER switch ON, place main light

switch to B.O. MARKER position, and check

front B.O. marker lights for operation.

Turn MASTER and main light switches OFF.

Do front B.O. marker lights operate?

Replace light switch (para 8-17).

B

1.

Reconnect bulkhead-to-drive's instrument

panel wiring harness to light switch.

2. Remove inoperative B.O. marker assembly

(para 8-22).

3. Place red lead of multimeters in center contact

of socket and black lead to ground.

4. Turn MASTER switch ON, place main light

switch to B.O. MARKER position, and check

for voltage.

5. Turn MASTER and light switches OFF.

Is voltage present?

Replace B.O. marker assembly (para 8-22).

CONTINUED ON NEXT PAGE

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