TM  55-1520-240-T 4-4.18  NO.  2  ENGINE  DOES  NOT  START  (ENGINE  IGNITION SYSTEM FAILURE (Continued) PULL OUT ENGINE 2 FIRE HANDLE.  DISCONNECT  PLUG FROM ENGINE NO. 2 IGNITION EXCITER. SET AND HOLD ENGINE  2  START   SW  T0 START. CHECK FOR 28VDC BETWEEN PLUG PIN A (+) AND GROUND. IS 28VDC PRESENT? NO DISCONNECT ENGINE TO AIRFRAME HARNESS AT DIS- CONNECT SHELF. SET AND HOLD  ENGINE  2  START   SW TO START. CHECK FOR 28VDC BETWEEN RECEPTACLE PIN 23 (+)  AND  GROUND.  IS  28VDC PRESENT? NO REMOVE ELECT PWR. LOWER OVHD PNL. CHECK FOR CON- TINUITY BETWEEN TERM 1 AND 2 OF  ENGINE  2  START WITH SW AT  START.  IS  CON. TINUITY PRESENT? REPLACE   ENGINE  2  START SW. YES RELEASE SW. DISCONNECT LEAD FROM ACCESSIBLE SPARK PLUG. CONNECT NEW SPARK PLUG TO LEAD. TAPE LEAD  TO  COMBUSTOR  HOUS- ING. CONNECT PLUG TO IGNl- TION EXCITER. HOLD  ENGINE 2 START  SW TO START.  DOES SPARK PLUG SPARK? REPLACE FOUR SPARK PLUGS. REPLACE IGNITION EXCITER. HOLD  ENGINE  2  START   SW TO START. DOES SPARK PLUG SPARK? FAULT CORRECTED. DISCON- NECT SPARK PLUG AND CON- NECT LEAD TO INSTALLED SPARK PLUG. DISCONNECT ENGINE TO AIRFRAME HARNESS PLUG ON ENGINE. CHECK FOR CON- YES TINUITY BETWEEN PLUG PIN 23 AND PLUG PIN L. IS CON- TINuITY PRESENT? YES LOCATE OPEN IN WIRE W559- 223-20,    W639-282-20    OR W592-19-20  BETWEEN  ENGINE 2 START SW AND RECEPTACLE 300J32. REPAIR OR REPLACE WIRE AS REQUIRED. NO REPLACE ENGINE TO AIRFRAME  HARNESS. YES REPLACE ENGINE HARNESS. 4-4.18 REPLACE IGNITION COIL AND CABLE ASSEMBLY. DISCON- NO NECT SPARK PLUG AND CON- NECT LEAD TO INSTALLED PLUG. END OF TASK 4-89/(4-90  blank)