TM 1-1520-238-T-4 4–102 4–21. ENG START NO 1 INDICATOR – IS NOT LIGHTED WITH ENGINE 1 STARTED 4–21 Tools: Nomenclature Part Number Tool Kit, Electrical SC518099CLA06 Repairer’s Multimeter, Digital AN/PSM-45 Personnel Required: 68F Aircraft Electrician One person to assist References: TM 1-1520-238-T-6 TM 1-1520-238-23 TM 55-2840-248-23 Equipment Conditions: Ref Condition TM 1-1520-238-23 Access provisions – LN1 door open 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 P39–4 . Is voltage present? YES Go to step 2. NO Go to step 3. 2. Check for open between P39–3 and P21–26. Does open exist? YES (ABY) Repair open wire. Go to paragraph 4–13. NO (ABZ) Replace wire harness (TM 1-1520-238-23). 3. Check for 28 VDC at J21–25. Is voltage present? YES (ABY) Repair open wire. Go to paragraph 4–13. (ABZ) Replace wire harness (TM 1-1520-238-23). NO Go to step 5. 4. Check for open between: P748–F and J21–26, P748–E and P173–R, P748–G and P173–P. Does open exist? YES Repair open wire. Go to paragraph 4–13. NO Go to step 6. 5. Check for 28 VDC at (A76)J1–c. Does open exist? YES Repair open wire between: P463–c and P439–A14, P439–A2 and J21–25. (A402): J21–A14 and TB2–8–A, J21–A2 and TB2–8–N. Go to paragraph 4–13. NO Refer to TM 1-1520-238-T-6 to troubleshoot circuit protection system (dc emergency bus – pilot station). 6. On pilot master caution/warning panel, depress PRESS TO TEST indicator. Is ENG START ENG 1 indicator lighted? YES Refer to TM 55-2840-248-23.to troubleshoot engine 1. NO Replace multi–channel dimming controller (TM 1-1520-238-23). END OF TASK