TM-9-2320-285-10
TRUCK TRACTOR, YARD TYPE, 43,500 LB GVW, DED, 4X2, ARMY MODEL M878A1
TECHNICAL MANUAL; OPERATOR’S MANUAL
JUNE 1985
TM-9-2320-285-10 - Page 16 of 121
TM 9-2320-285-10
1-15.
ELECTRICAL SYSTEM (Continued)
c.
Switches and Indicator Lights (continued).
Key Switch - Four position switch controls power to vehicle electrical circuits; first clockwise position delivers power to all
circuits except starter, second clockwise position cranks starter, first counterclockwise position delivers power to
accessory circuits only.
Key removes in original (OFF) position.
24V INVERTER Switch - Converts tractor 12V output to 24V to enable connecting cable to power 24V trailer lighting
system.
Push up to turn ON, down to turn OFF.
Turn ON only when connecting to trailer with 24V lighting system.
Indicator Lights Eight light assemblies, each with incandescent lamp and red lens.
With engine running, WATER LEVEL,
WATER TEMP, OIL PRESSURE, LOW AIR, and TRANS/TORQUE CONVERTER Lights glow red to signal malfunction.
24V INVERTER Light glows red when 24V INVERTER switch is on.
High Beam light glows red when headlights are on
high beam.
LOW FUEL INDICATOR light glows red when fuel level in tank is too low for operation.
1-16.
COOLING SYSTEM
Radiator - Tube-and-fin type.
Engine coolant circulated through radiator where it gives up heat to air stream developed by
belt driven fan.
Engine driven water pump draws cooled coolant from bottom of radiator and discharges it into lower part
of cylinder block.
1-11
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