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 235 of 828
TM 9–2350–311–20–2
3–123
j.
NBC SYSTEM CIRCUIT — CONTINUED
(1)
NBC CONTROL BOX ASSEMBLY INDICATOR
LIGHT DOES NOT ILLUMINATE, BUT NBC
SYSTEM OPERATES.
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.
Remove lens and LED from NBC control box
assembly (para 17–4).
2.
Turn MASTER and CAB NBC POWER
switches to ON.
3.
Place red multimeter lead in LED housing and
black lead to ground.
4.
Check for voltage.
Is battery voltage present?
A
yes
no
Replace LED (para 17–4).
CONTINUED ON NEXT PAGE
CAB NBC
POWER SWITCH
+–
1.
Turn MASTER and CAB NBC POWER switches
to OFF.
2.
Install lens and LED in NBC control box
assembly (para 17–4).
3.
Remove cover from NBC control box assembly.
4.
Place one multimeter lead on X2 terminal of
electromagnetic relay K1 and other lead to
positive terminal on LED housing DS1.
5.
Check for continuity.
Is continuity present?
yes
no
B
+
LED
HOUSING
DS1
Repair wire 5 (para 17–4).
NBC CONTROL
BOX ASSEMBLY
X2 TERMINAL
WIRE 5
NBC CONTROL
BOX ASSEMBLY
DS1 TERMINAL
–
RELAY K1
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