TM 1-1520-238-T-6 9–302 9–105. LT UTIL SEC CIRCUIT BREAKER (CB23) – DOES NOT STAY CLOSED 9–105 Tools: Nomenclature Part Number Tool Kit, Electrical SC518099CLA06 Repairer’s Multimeter, Digital AN/PSM-45 Personnel Required: 68X Armament/Electrical Systems Repairer References: TM 1-1520-238-23 WARNING Turn off power before detaching or attaching wires and connectors. High current 28 VDC or 115 VAC is present. Failure to do so could result in death or serious injury. 1. Check for short between (A76): J1-U and ground, J1-W and ground. Does short exist? YES Go to paragraph 9–263 to troubleshoot circuit protection system (dc emergency bus – pilot station). NO Go to step 2. 2. Detach DS16 SP1. Check for short between P463-w and ground. Does short exist? YES Repair shorted wire between P463-W and DS16 SP1. Go to paragraph 9–104. NO Go to step 3. 3. Attach DS16 SP1. Check for resistance between P463-W and ground. Is resistance present? YES Go to step 4. NO Replace pilot utility light (TM 1-1520-238-23). 4. Detach P100. On pilot center circuit breaker panel, open LT UTIL SEC circuit breaker (CB23). On pilot EXT LT/INTR LT panel, set FLOOD switch to OFF. Check for short between DS16 SP1 and ground. Does short exist? YES Repair shorted wire between: DS16 SP1 and P463-W, P463-U and P100-B5. Go to paragraph 9–103. NO Go to step 5. 5. Check for resistance between (A325): P1-A1 and ground, P1-A2 and ground, P1-A4 and ground, P1-A5 and ground, P1-A6 and ground, P1-A7 and ground, P1-A8 and ground. Is resistance present? YES Replace pilot EXT LT/INTR LT panel (TM 1-1520-238-23). NO Repair shorted wire between (A325): P1-A1 and XDS3, P1-A2 and XDS1, P1-A4 and XDS6, P1-A5 and XDS2, P1-A6 and XDS5, P1-A7 and XDS7, P1-A8 and XDS4. Go to paragraph 9–103. END OF TASK