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 243 of 828

TM 9–2350–311–20–2

3–131

j.

NBC SYSTEM CIRCUIT — CONTINUED

(4)

NBC CONTROL BOX ASSEMBLY INDICATOR

LIGHT ILLUMINATES, BUT GUNNER’S M3

ELECTRICAL AIR HEATER DOES NOT OPER-

ATE.

INITIAL SETUP

Applicable Configuration

M109A4/M109A5 howitzers

Test Equipment

Multimeter (item 6, Appx H)

Tools

Artillery and turret mechanic’s tool kit

(SC 5180–95–CL–A12)

Equipment Condition

Vehicle MASTER switch to OFF (TM 9–2350–311–10)

CAB NBC POWER switch to OFF (TM 9–2350–311–10)

1.

Disconnect wire 136A from gunner’s M3

electrical air heater.

2.

Turn MASTER and CAB NBC POWER

switches to ON.

3.

Place red multimeter lead in wire 136A and

black lead to ground.

4.

Check for voltage.

Is battery voltage present?

yes

no

A

B

Replace M3 electrical air

heater (para 17–2).

CONTINUED ON NEXT PAGE

WIRE 136A

–+

GUNNER’S

HEATER

WIRE 136A

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 136A and other

lead to pin E of NBC power lead assembly

connector.

4.

Check for continuity.

Is continuity present?

–

+

POWER LEAD

ASSEMBLY

CONNECTOR

PIN E