TM-9-2350-311-20-2

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

TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR CAB, ARMAMENT, SIGHTING AND FIRE CONTROL, ELEVATING AND TRAVERSING SYSTEMS AND ASSOCIATED COMPONENTS

DECEMBER 1993

TM-9-2350-311-20-2 - Page 236 of 828

TM 9–2350–311–20–2

3–124

3–3

TROUBLESHOOTING — CONTINUED

j.

NBC SYSTEM CIRCUIT — CONTINUED

(1)

NBC CONTROL BOX ASSEMBLY INDICATOR

LIGHT DOES NOT ILLUMINATE, BUT NBC

SYSTEM OPERATES – CONTINUED.

C

1.

Place one multimeter lead on X1 terminal of

electromagnetic relay K1 and other lead to

negative terminal on LED housing DS1.

2.

Check for continuity.

Is continuity present?

yes

no

Repair wire 4 (para 17–4).

Replace LED housing

DS1.

END OF TASK

RELAY K1

–

CONTINUED FROM STEP B

DS1 TERMINAL

X1 TERMINAL

+

LED HOUSING

DS1

WIRE 4