ARMY TM  5-6115-612-12 MARINE  CORPS  TM  6115-12/7 AIR  FORCE TO 35C2-3-471-1 NAVY AG-320B0-0MM-000 Section XI. MAINTENANCE  OF  IGNITION  SYSTEM 4-44. GENERAL. The  ignition  system consists  of  a  spark  igniter,  ignition coi1, and the high tension electrical leads. The  purpose  of  the  ignition system is to ignite the fuel-air mix- ture in the engine combustor. Input voltage to the ignition coil charges a capacitor. As  the  capacitor  becomes fully  charged, current  is  forced  from the  ignition  coil,  through  the  high tension electrical leads, to the spark igniter. As  this  action  continues, resistance in the air gap of the spark igniter is overcome, causing the capa- citor  to  discharge  completely. The discharge  is  in  the  form  of  a  spark with a minimum 5000 volts. This  entire process   is   repeated   240   times   per minute. NOTE If not specified in maintenance procedure, apply torque     in accordance with table 1-1, Torque Specifications. 4-45. IGNITION SYSTEM TEST. The following test procedure can be used to isolate  the  ignition  system  component requiring  service  or  replacement. a. Access. (1) Gain access to fuel housing (paragraph  4-34a). (2) Disconnect electrical con- nector from electrical high pressure fuel  pump. (3) Loosen turnlock fasteners and remove  engine  housing  access  cover. (4) Open control panel access door. b. Test. WARNING High voltage is   present   when ignition system is energized. To prevent injury, use extreme cau- tion when working with energized equipment. (1)  Remove spark igniter  (1, figure 4-31) and place on top of engine. (2)  On  the  control  panel,  move MASTER  SWITCH  to  RUN,  then  place  in START position. (3)  Observe sparking  on spark igniter. (4)  If  there  is  a  steady,  blue spark,  ignition  system  components  are operating  properly. (5)  If there is a weak, intermittent  orange  spark, disconnect input   lead   (4)   from   ignition   coil (13). Check  voltage  at  input  lead. Voltage  should  read  16-24  Vdc. (6) If voltage is incorrect and battery is good, problem is in engine electronic control module  (EECM)  or associated wiring. Refer to paragraph 4-64. (7) If voltage is correct, recon- nect input lead (4) to ignition coil (13) and replace high tension lead (9) (paragraph 4-46). (8) Repeat test. If   spark   is still  weak, intermittent,  and  orange, service   or replace spark Igniter (paragraph 4-47). (9)  Repeat  test. If  spark  is still weak, intermittent, and orange, replace  ignition  coil  (paragraph  4-48). 4-101