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 58 of 926
TM 9-2320-283-20-1
PRINCIPLES OF OPERATION.
1-15.
ELECTRICAL SYSTEM (Continued).
c.
Service Lighting System (Continued).
(3)
Turn Signal and Hazard Warning Lamps.
When the blackout toggle switch is in NORMAL position, battery power is applied to the turn signal switch to
illuminate right or left front turn signals and rear turn signals as well as trailer turn signals through tractor-mounted
connector.
Also, the turn signal switch contains a hazard warning switch that allows the operator to flash all lamps in the
turn signal system simultaneously.
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.
CIRCUIT BREAKER (CB-5).Protects electrical
components of
flasher, turn signal
switch, and hazard
warning
switch
circuits by
opening
when load exceeds 20 amperes.
May be manually reset by pressing CB-5 button in. CIRCUIT
BREAKER (CB-8).
Protects electrical
components of
24-volt relay and circuits by opening when load exceeds 20
amperes.
May be manually reset by pressing CB-8 button in.
BLACKOUT TOGGLE SWITCH.Two-position switch for normal and blackout modes of
operation.
When set
to
NORMAL
position, 12-volt power
from circuit breaker (CB-5) passes through switch contacts to turn signal switch, flasher
unit, and hazard warning switch.
FLASHER UNIT.
Receives 12-volt power from blackout toggle switch in NORMAL position and supplies this power
alternately on and off to turn signal control or hazard warning switch when either one is engaged.
TURN SIGNAL SWITCH.
When engaged, it receives 12-volt power from flasher unit.
(The flasher
unit receives
12-volt
power through
blackout toggle switch and circuit breaker CB-5).
Power is then supplied to:
(a)
Front left or right turn signals.
(b)
Rear left or right turn signals.
(c)
12-volt trailer connector.
(d)
Relays RY-2 and RY-3 (to supply power to both tractor mounted 24-volt connectors for trailer turn signals).
1-38
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