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TM-9-2350-311-20-2 Maintenance Manual Volume 2 for M109 Cab Download

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