TM 9-2320-302-20 0010 00-13 Table 1. Electrical System Troubleshooting Procedures - Continued. MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION Electric Horn Circuits - Continued Electric Horn Does Not Operate - Continued. 8.    Disconnect lead 26 from horn. Check for +12 VDC at lead 26 with horn button pressed. If +12 VDC is present, go to step 9.    If    voltage    is    not    present, disconnect  horn  relay  and  check for  continuity  between  connector 87  and  lead  26.  If  continuity  is indicated, replace horn relay (WP 0071   00).   If   continuity   is   not indicated, repair lead 26 (WP 0119 00). 9.    Disconnect  ground  lead  from horn.    Check    for    continuity between     ground     lead     and ground. If continuity is indicated, replace horn (WP 0112 00). If continuity is not indicated, repair ground lead (WP 0119 00). Tractor Beacon Light Circuits Tractor Beacon Light Does Not Operate. 1.    Check    tractor    beacon    light 15A fuse. Replace 15A fuse if defective (WP 0071 00). 2.    Remove    lamp    from    tractor beacon light. Check for continuity    between    contacts on lamp. If  continuity  is  indicated,  go  to step     3.     If     continuity     is     not indicated,  replace  tractor  beacon light (TM 9-2320-302-10). 3.    Disconnect   lead   254A   from tractor beacon light. Check for +12  VDC  at  lead  254A  with beacon    light    switch    in    on position. If voltage is not present, go to step 4. If +12 VDC is present, check for continuity    between    socket    and ground. If continuity is indicated, replace  tractor  beacon  light  (TM 9-2320-302-10).   If   continuity   is not  indicated,  repair  ground  lead (WP 0119 00). 4.    Remove   tractor   beacon   light 15A fuse. Check for +12 VDC at  lead  420JD  fuse  connector from auxiliary light power bus. If +12 VDC is present, go to step 5. If voltage is not present, repair lead 420JD (WP 0119 00). 5.    Disconnect    lead    254    from beacon light switch. Check for +12 VDC at lead 254. If +12 VDC is present, go to step 6. If voltage is not present, repair lead 254 (WP 0119 00). 6.    Disconnect lead 254 and lead 254A   from   switch.   Activate switch.  Check  for  continuity between contacts of switch. If  continuity  is  indicated,  go  to step     7.     If     continuity     is     not indicated,    replace    beacon    light switch (WP 0065 00). 7.    Disconnect   lead   254A   from tractor beacon light. Check for +12 VDC at lead 254A. If   voltage   is   not   present,   repair lead 254A between beacon lights and beacon light switch (WP 0119 00).