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 245 of 828

TM 9–2350–311–20–2

3–133

j.

NBC SYSTEM CIRCUIT — CONTINUED

(5)

NBC CONTROL BOX ASSEMBLY INDICATOR

LIGHT ILLUMINATES, BUT CANNONEER NO.

1’S M3 ELECTRICAL AIR HEATER DOES NOT

OPERATE.

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)

NBC POWER LEAD

ASSEMBLY CONNECTOR

PIN A

1.

Disconnect lead 136B from cannoneer no. 1’s

M3 electrical air heater.

2.

Turn MASTER and CAB NBC POWER

switches to ON.

3.

Place red multimeter lead in wire 136B and

black lead to ground.

4.

Check for voltage.

Is battery voltage present?

A

yes

no

Replace M3 electrical

air heater (para 17–2).

B

CONTINUED ON NEXT PAGE

WIRE 136B

WIRE 136B

–+

GUNNER’S

HEATER

–

+

1.

Turn MASTER and CAB NBC POWER

switches to OFF.

2.

Disconnect NBC power lead assembly at J2

connector on NBC control box assembly.

3.

Place one multimeter lead in wire 136B and

other lead to pin A of NBC power lead

assembly connector.

4.

Check for continuity.