TM 1-1510-225-10 3A-27 Table 3A-2.  EFIS Display Color Codes COLOR TYPE OF INFORMATION Red Warnings Yellow Cautions or abnormal source; Cross-side navigation data; Cross-side commanded data; Cross-side    selected    active    route/ flight plan Green On-side   approach   and   navigation data; On-side commanded data; Selected active route/flight plan White Scales and associated figures;   Held DME distance display Cyan On-side    non-approach    navigation data (LNAV) Orange Selected heading/DME HOLD annunciation Matches NAV data color Selected source b.  Electronic Flight Instrument System Preflight Test. NOTE Performing    the    EFIS    self    test    is    not required at any time.  If a failure exists, the small red SG in a red box is displayed.  The self-test is intended to familiarize the pilot with   the   display   flags,   and   for   checking proper display color. 1.   BRT control – Set desired brightness. 2.   TST / REF push-button switch  – Press for 3 seconds.  A SELF TEST PASS or SELF TEST FAIL message will be annunciated. NOTE White on the compass scale indicates that all    three    colors    are    operational    in    the display unit. 3A-18.  EFIS STANDBY POWER SYSTEM. The    EFIS    standby    power    system    provides standby  electrical  power  for  EFIS  system  operation when   aircraft   electrical   power   is   unavailable.      The EFIS  standby  power  system  control  panel  is  located on the instrument panel.  A push-button switch on the control  panel,  placarded   TEST,  initiates  self  test.    A switch indicator, placarded  ARM TEST on the top half and   ARM   on   the   bottom   half,   is   used   to   select   or deselect the armed condition of the system, indicates if self  test  is  in  progress,  and  indicates  whether  or  not the system is armed or not.  The standby EFIS power system  is  protected  by  a  15-ampere  circuit  breaker, placarded    EFIS    AUX    BAT,    located    on    the    right sidewall circuit breaker panel, Figure 2-6. 3A-19.  EFIS CONTROL PANEL. a.   Description.          The     EFIS     control     panel enables    each    pilot    to    control    formatting    on    his respective EHSI and EADI and to select the source of navigation, attitude, and heading information.  Refer to Figure 3A-10. b.  EFIS  Control  Panel  Controls,  Indicators, and Functions.  (1)   Radio     Altimeter     Decision     Height     Set Knob.    The  radio  altimeter  decision  height  set  knob, placarded   DH,   is   used   to   set   the   desired   decision height  in  feet  that  is  shown  in  the  green   DH  display located  in  the  lower  left  comer  of  each  EADI.    To  set the decision height, pull out the knob and then turn it clockwise  to  increase  the  selected  decision  height  or counterclockwise   to   decrease   the   selected   decision height.    The  decision  height  set  knob  is  variable  rate; that  is,  turning  the  knob  farther  in  either  direction  will increase    the    rate    of    change    in    selected    decision height.    The  decision  height  selection  range  is  from OFF (-1 foot) to 2500 feet. Push   the   DH   knob   back   in   after   the   decision height has been set to lock the selected  DH altitude.  If the  DH  is set to   OFF the   DH  annunciator  will  not  be displayed on the EADI. (2)   HSI   360   Degree   Push-Button   Selector Switch.     The  HSI  360  push-button  selector  switch, placarded  HSI,  is  used  to  select  one  of  four  possible 360°   formats   for   the   HSI.      Each   press   of   the   HSI switch sequences to the next display format.  The four possible 360° HSI formats are Standard HSI compass rose;  Navigation  map;  Navigation  map  with  weather radar display, and Directional gyro mode. (3)   Radio Altimeter Push-Button Test Switch.   Pressing   the   radio   altimeter   test   switch,   placarded RALT  TST,  provides  a   discrete  output  to  the  radio altimeter initiating its self-test function.