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 242 of 828

TM 9–2350–311–20–2

3–130

3–3

TROUBLESHOOTING — CONTINUED

j.

NBC SYSTEM CIRCUIT — CONTINUED

(3)

NBC CONTROL BOX ASSEMBLY INDICATOR

LIGHT ILLUMINATES, BUT M2A2 AIR PURI-

FIER DOES NOT OPERATE. —

CONTINUED

1.

Reconnect lead 135 to M2A2 air purifier.

2.

Place one multimeter lead in socket B and other

lead to pin B of J2 connector on NBC control

box assembly.

3.

Check for continuity.

Is continuity present?

CONTINUED FROM STEP B

C

yes

no

Repair wire 135 of NBC

power lead assembly

(para 8–9).

D

yes

no

Replace J2 connector

of NBC control box as-

sembly (para 17–4).

Repair wire 9 (para

17–4).

END OF TASK

WIRE 9

1.

Turn MASTER and CAB NBC POWER switches

to OFF.

2.

Disconnect NBC power lead assembly at J2

connector of NBC control box assembly.

3.

Place one multimeter lead in wire 135 and other

lead to pin B of NBC power lead assembly

connector.

4.

Check for continuity.

Is continuity present?

J2 CONNECTOR

SOCKET B

J2 CONNECTOR PIN B

NBC CONTROL BOX

ASSEMBLY

WIRE 135

+–

NBC POWER LEAD

ASSEMBLY CONNECTOR

PIN B

+

–