TM  9-2320-387-24-l REFERENCE   INFORMATION If the  engine   cranks   ok  (or  starts),   then  the  batteries   are good   enough    for  testing   the  glow  plugs.   If  the  engine starts,   shut   it off. You  can  use STEXE Test  10  to  measure   cranking   speed. The  engine  should   crank   at  least   100  rpm  in  cold  weather and  at  least   180  rpm  in warm  weather. GLOW  PLUGS  CIRCUIT NOTE The WAIT-TO-START lamp    is  NOT diagnosed    in this  section.   If the  lamp does   not  work   properly,   the  glow  plug circuit   may  be  affecting   Its  operation. Run  these   tests  to  check   out  the  glow plug  circuit.    If the  lamp  still  does  not  work properly,    go  to  the  INSTRUMENT     section for  a full  diagnosis   of  the  lamp’s   problem. 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 result   in  damage   to equipment or  injury  to  Personnel. BAD   CONNECTIONS ARE   THF   MOST   COMMON PROBLEM ! Sometimes    just  disconnecting, cleaning,   and reconnecting     will  solve   a  problem. BE  THOROUGH! The  time  you   save   may   be  your   own.   Refer  to  the functional    flow  schematic    and   check   the  following: 1. BAlTERY -  make   sure  all  connections    are  clean   and tight.   including   the  shunt   and   power   stud. 2.  PROTECTIVE CQNTROL    BOX  -  remove   BOTH connectors     and  look  for  bent   or  broken   pins,  pins pushed    out  of  their  socket.    or  dirt  and  corrosion   in  the connections. 3.  GLOW   PLUG   CONTROLLER - pop  the  controller connector    off  (squeeze    the  sides)  and  check   the  pins   in both   the  controller    and  the   connector. Look  for  bent. broken    or  pushed   out  pins,   die,  or  corrosion. Check   for broken   wires   at  the  connector. Take   note  that   pin  2  of the   glow   plugs   controller    connector    has  no  pin  in  it. 4.  GLOW   PLUGS   -  check   that   all  the  glow  plug  wires   are snug.     Don’t  just  look  with   your   eyes.     Many   problems are  solved   by  looking   with   your   fingers   to  be  sure    a connection     is snug. NORMAL GLOW   PLUG   OPERATION The   glow   plugs   first  come   ON  when   the  engine   temperature is below    120  “F  (49°C)   and   the  rotary   switch   is turned   lo RUN.   They   stay   ON  for  up  to  9  seconds   and  then   go  OFF. They   will  stay   OFF  for  about   7-15   sewnds     then   come   ON CONTROLLER HARNESS again   for  about   1 second. NOTE BAlTERY 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    lo  battery current,    100  millivolts   =  1,000  amps.   To  get current,    multiply   millivolts   x  10. I BAlTERY    CURRENT STEIICE-R   TEST  80 I To  check    for   glow    plug    current draw,  start  STE/lCE-R    Test  80,  Battery   Current.    Turn   off  all accessories     (lights,   heater,   wipers,   etc.).    STE/ICE-R    should   immediately     measure   at  least 74  amps.    Take   note,  however,     that   if  all  your    glow    plugs    are  working, the   current     draw should   be  close   to  or  more   than  100  amps,  especially    if it’s  cold.     If  it’s   near   freezing    and the   glow    plugs    only    draw    75-60   amps,   you    probably have    a  few   bad   glow    plugs. 2-291