TM 1-1510-218-10 3-86 (9)   IDENT   /   OUT   /   MIC   Switch.      Selects source of aircraft identification signal. (a)  IDENT   –   Activates   transmission   of identification (IP) pulse. (b)  OUT – Disables IDENT MIC. (c)  MIC    –    Enables    the    POS    IDENT button   located   only   on   the   pilot's   side    CONTROL wheel  to  activate  transmission  of   IDENT  signal  from transponder. (10)   MODE  4  REPLY  Indicator  –  Illumination indicates that a reply has been made to a valid Mode 4 interrogation or will flash when in standby position and interrogated for Mode 4. (11)   MODE 4 AUDIO / LIGHT / OUT Switch. If the MODE 4 computer is installed in the aircraft,  place  the  AUDIO  /  LIGHT  /  OUT switch   in   the   AUDIO   or   LIGHT   position during  flight  operations.    Do  not  use  the OUT position. (a)  AUDIO  –  Permits  aural  and  REPLY light   monitoring   of   valid   Mode   4   interrogations   and replies. (b)  LIGHT   –   Permits   REPLY   indicator only monitoring. (c)  OUT – Disables monitoring capability. (12)   MODE 3/A CODE Selectors – Selects the desired reply codes for mode 3/A operations. NOTE The  cover  over  the  MODE  select  switches must    be    slid    forward    to    display    the selected MODE 2 code. (13)   MODE  2  CODE  Selectors  – Selects the desired reply code for mode 2 operations. (14)   MODE  1  CODE  Selectors  – Selects the desired reply code for mode 1 operations. (15)   MODE 4 TEST / ON / OUT Switch. (a)  TEST    –    Initiates    BIT    of    Mode    4 operation. (b)  ON – Enables Mode 4 operation. (c)  OUT – Disables MODE 4 operation. (16)   MODE  4  CODE  Control.    Selects  dialed in Mode 4 CODE of the day. (17)   M–C TEST Switch. (a)  TEST    –    Permits    self-test    in    the selected mode. (b)  ON   –   Permits   set   to   reply   in   the selected mode. (c)  OUT – Disables replies. (18)   M–3/A TEST Switch. (a)  TEST    –    Permits    self-test    in    the selected mode. (b)  ON   –   Permits   set   to   reply   in   the selected mode. (c)  OUT – Disables replies. (19)   M-2 TEST Switch. (a)  TEST    –    Permits    self–test    in    the selected mode. (b)  ON   –   Permits   set   to   reply   in   the selected mode. (c)  OUT – Disables replies. (20)   M-1 TEST Switch. (a)  TEST    –    Permits    self–test    in    the selected mode. (b)  ON   –   Permits   set   to   reply   in   the selected mode. (c)  OUT – Disables replies. NOTE There  is  a  POS  IDENT  button,  located  on the   pilot's   and   copilot's   control   wheels, which, when pressed, activates transponder identification. c.    Normal Operation. (1)   Turn-on Procedure.  Set MASTER switch to STBY.  Depending on the type of receiver installed, WARNING