TM-9-2320-387-24-1
TRUCK, UTILITY: S250 SHELTER CARRIER, 4X4, M1113
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE, VOLUME 1
DECEMBER 1997
CHANGE 1
TM-9-2320-387-24-1 - Page 346 of 1205
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
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