TM-9-2320-283-20-1
TRUCK TRACTOR, LINE HAUL, 50,000 GVWR, 6X4, M915A1
TECHNICAL MANUAL; ORGANIZATIONAL MAINTENANCE PART 1 OF 3
DECEMBER 1983
TM-9-2320-283-20-1 - Page 51 of 926
TM 9-2320-283-20-1
PRINCIPLES OF OPERATION.
1-15.
ELECTRICAL SYSTEM.
a.
Starting System.
BATTERY PACK.
Consists of
four, 12-volt, maintenance free batteries.
Two batteries are wired in parallel in each set.
Each set is connected in series for 24-volt
output.
Battery
pack
is used
for both
12-volt
and 24-volt output.
STARTER MOTOR.
When energized,
motor engages with ring gear
on flex plate
(flywheel) to start engine.
STARTER MOTOR SOLENOID.
24-volt power
is applied to starter solenoid
when starter
relay is
energized.
Solenoid
closes
and supplies
24-volt power, which energizes starter motor.
STARTER
RELAY.
With ignition
switch in
ON
position, transmission
shift control lever in neutral, and ENGINE START
button depressed, relay energizes and closes starter solenoid circuit.
IGNITION
SWITCH.
Supplies
24-volt
power to
relay (RY-9), which
in turn provides 12-volt power to electrical system,
including engine starting system circuit.
SOLENOID SHUTOFF VALVE.
Normally closed.
When the ignition switch is turned to
ON position, valve opens allowing
fuel to pass to injectors.
(Refer to paragraph 1-12 for description of fuel system).
NEUTRAL SAFETY SWITCH.
Normally open.
Prevents starting circuit from being activated when transmission shift
control lever is in any position other than neutral.
ENGINE START BUTTON.
Activates starting circuit by energizing the starter relay.
TA 236768
1-31
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