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 50 of 926
TM 9-2320-283-20-1
PRINCIPLES OF OPERATION.
1-14.
COOLING SYSTEM (Continued).
b.
Coolant Temperature Monitoring 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.
IGNITION SWITCH.
Supplies 24-volts to relay (RY-9), which in
turn provides 12-volt power to electrical system, including
coolant temperature monitoring system.
RELAY (RY-9).
Energized by 24-volts from ignition switch.
When
energized,
RY-9 supplies 12-volt power to circuit
breaker (CB-2).
CIRCUIT BREAKER (CB-2).
Protects electrical components and wiring of coolant system by opening circuit when load
exceeds 20 amperes.
May be manually reset by pressing CB-2 button in.
WATER TEMPERATURE GAGE.
Shows coolant temperature when actuated by electrical signal from water temperature
sending unit.
WATER
TEMPERATURE
SWITCH.
Normally
open
switch
is
closed to
activate indicator lamp when coolant
temperature exceeds 2250F.
ENGINE COOLANT
TEMPERATURE WARNING LAMP.
Activated by
12-volt power
from water temperature switch
when engine temperature exceeds 225°F.
WATER TEMPERATURE SENDING UNIT.
Provides electrical signal to temperature gage.
TA 236767
1-30
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