TM 1-1520-238-T-5 7–117 7–37. RTR BK INDICATOR – IS NOT LIGHTED 7–37 Tools: Nomenclature Part Number Tool Kit, Electrical SC518099CLA06 Repairer’s Multimeter, Digital AN/PSM-45 Personnel Required: 68X Armament/Electrical Systems Repairer (2) References: TM 1-1520-238-T-6 TM 1-1520-238-23 Equipment Conditions: Ref Condition Paragraph 7–21 Rotor brake engaged 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 28 VDC at P1072–B. Is voltage present? YES Go to step 3. NO Go to step 2. 2. Check for 28 VDC at (A76)J1–n. Is voltage present? YES Repair open wire between: P463–n and P441–A3, P442–A4 and P1072–B, (A402): J5–A4 and TB2–9–P, J24–A3 and TB2–9–N, or replace TB2–9. Go to paragraph 7–21. NO Refer to TM 1-1520-238-T-6 to troubleshoot circuit protection system (dc emergency bus – pilot station). 3. Check for open between S88–A and S88–B. Does open exist? YES Replace rotor brake pressure switch (S88) (TM 1-1520-238-23). NO Go to step 4. 4. Check for 28 VDC at (A402)J16–B17. Is voltage present? YES Go to step 5. NO Repair open wire between: P442–A2 and P1072–A, (A402): J16–B17 and TB2–9–T, J5–A2 and TB2–9–W, or replace TB2–9. Go to paragraph 7–21. 5. Check for open between P18–2 and P440–B17. Does open exist? YES Repair open wire. Go to paragraph 7–21. NO Refer to TM 1-1520-238-T-6 to troubleshoot pilot and CPG caution/warning system. END OF TASK