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 240 of 828

TM 9–2350–311–20–2

3–128

3–3

TROUBLESHOOTING — CONTINUED

j.

NBC SYSTEM CIRCUIT — CONTINUED

(2)

NBC SYSTEM DOES NOT OPERATE.

—

CONTINUED

Replace wire 13 (para

17–4).

1.

Place one multimeter lead to X1 terminal on

electromagnetic relay K1 and other lead to

GND terminal of electromagnetic relay K1.

2.

Check for continuity.

Is continuity present?

Replace wire 2.

yes

no

I

CONTINUED FROM STEP H

yes

no

Replace ground wire 7

(para 17–4).

J

yes

no

Replace electromagnetic

relay K1 (para 17–4). If

malfunction persists, in-

spect NBC power lead as-

sembly and repair if dam-

aged (para 8–9).

END OF TASK

+–

+–

X1 TERMINAL

GROUND

WIRE 7

RELAY K1

GND TERMINAL

GND TERMINAL

J2 CONNECTOR

GND TERMINAL

GROUND WIRE 13

RELAY K1

1.

Place one multimeter lead to GND terminal of

electromagnetic relay K1 and other lead to

GND terminal of J2 connector on NBC control

box assembly.

2.

Check for continuity.

Is continuity present?

NBC CONTROL

BOX ASSEMBLY