TM  9-2320-387-24-I REFERENCE   INFORMATION GLOW  PLUGS  CIRCUIT Dead   glow   plugs   draw  virtually    no  current, but  other   parts   of  the  vehicle    are  drawing some   current-up    to  8 amps.     If  any   glow plugs   are  drawing   any  current,   then   the PCB   is probably    OK. I For  a  good   description    of  how   glow   plugs   cycle and   how  to  check   for  proper   cycling,    refer  to page   2-293. --I @ WARNING Disconnect negative battery cable before    disconnecting and  reconnecting PCB   harness. WARNING There   is  battery   voltage   at the  PCB  at all  times.     Failure   to   disconnect battery cable    will   nsult in  damage    to equipment    or  injury   to  Personnel. If most or all of the glow plugs are  bad,  you may  also  have   a  problem   with   the  PCB   or  the glow  plug  controller    which   caused   them   to  go bad   (usually   they   bum  out  from   being   on  too long  or  not  turning   off  at  all).    After   replacing the  bad  glow   plugs,   rerun   the  glow   plugs   test chain   paying    special   attention    to  the  glow   plugs cycling,   especially    that  they   turn  OFF  when they   should. 1 Replace   glow   plugs,  wires,   or  harness   (para.   3-39). BATTERY   CURRENT STE’ICE-R   TEST  80 1. Start Test   80.  Battery   Current. 2.  Displayed    reading   is in  amps.    The   reading   will  be greater   then   30  amps,   depending    on  how   many accessories    you   have   on. BATTERY   CURRENT MULTIMETER 1. Set  the  voltmeter    to  a  DC  volts   scale  of  about   1 volt. 2.  Connect    the  BLACK   lead  to  the  battery    side  of  the current shunt   and  the   RED    lead  to  the   other   end  of the  current   shunt. 3.  Current   shunt   voltage    is  proportional    to  battery current,    100  millivolts   =  1.000   amps.    To  get  current, multiply   millivolts   x  10. CHECKING     GLOW   PLUGS   8  THEIR   WIRFS 1.  Disconnect    ALL  the  glow   plugs. 2.   Disconnect    the  neoative    battery    cable.    Disconnect    the  PCB connector    harnessfrom the   PdB. Reconnect    the  negative battery   cable.     Measure   me   resistance    between    pin  D  in the engine   connector    harness   of  the  PCB   and   ground.     There should   NOT  be  continuity    (resistance    reading   off  the  scale). If there   is continuity,     repair   or  replace   me  harness. Repeat   the  following    for  each   glow   plug: 3. a.   Reconnect    the  wiring   harness   to  the  glow   plug  while   you repeat   the  resistance    measurement     described    in  step  2. When  you   reconnect    the  wire  to  the  glow   plug,   the resistance    should   drop   to  between    1 and  2  ohms   (glow plugs  are  typically    1.6  ohms). b.   If  step  A  passed: disconnect    the  glowptug    again,   making   sure   the  resistance goes   off  scale  again.     Repeat   step  A  for  me  next   glow plug. C. If  step  A  failed: then   either   the  glow  plug   or  its  wire  is no  good.    Take   the wire  off  the  glow   plug  again   and  measure    the   resistance from  the  glow   plug  to  the  engine   block.   If the   resistance    is 1 - 2  ohms,   then   the  cable   is  no  good.   Otherwise    replace the  glow   plug   and  check   the   cable   for  continuity,    just  to  be sure. 4.    Reconnect    the   PCB  and  all  wires. 2-295