TM-9-2320-272-10
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; OPERATOR'S MANUAL
SEPTEMBER 2004
CHANGE 2
TM-9-2320-272-10 - Page 102 of 481
2-3. CHASSIS CONTROLS AND INDICATORS (Contd)
TM 9-2320-272-10
Change 2
2-3
Key
Item and Function
14
PRIMARY AIR PRESSURE GAUGE indicates air pressure in the primary
brake system. Normal pressure is 90-130 psi (621-896 kPa).
15
DEFROSTER CONTROL opens vents to direct heated air at the windshield.
16
HEAT VENT CONTROL controls the amount of heat blown into the cab by
adjusting the opening of heat ventilation doors.
17
FRESH AIR VENT CONTROL pulls out to open ventilation doors, allowing
outside air to circulate in the cab.
18
GRAB HANDLE aids crewmembers in entering and exiting vehicle cab.
Handle is also a brace for crewmembers during travel.
19
FLOODLIGHT CONTROL SWITCH (M936/A1/A2 models) turns on
floodlights installed on wrecker body for use in night crane operations.
20
ELECTRICAL RECEPTACLE OUTLET (M936/A1/A2 models) provides
battery voltage for extension cord trouble light.
21
AUXILIARY OUTLET RECEPTACLE (M936/A1/A2 models) is plugged into
electrical receptacle outlet. A trouble light is then plugged into the auxiliary
outlet receptacle in order to be powered by vehicle batteries.
22
SPRING BRAKE RELEASE CONTROL is pushed in to release spring
brakes independently of the mechanical parking brake. Control is used to
release spring brakes in order to test and adjust mechanical brakes.
23
VOLTMETER indicates charging condition of the batteries.
24
SECONDARY AIR PRESSURE GAUGE indicates air pressure in the
secondary brake system. Normal pressure is 90-130 psi (621-896 kPa).
25
TRANSMISSION OIL TEMPERATURE GAUGE indicates temperature of
transmission oil. Normal operating temperature is 120°-220°F (49°-104°C).
26
ENGINE OIL PRESSURE GAUGE indicates oil pressure when engine is
running. Normal operating pressure at idle is 15 psi (103 kPa).
27
FUEL GAUGE indicates fuel level in fuel tank(s).
28
AMBER WARNING LIGHT SWITCH (M936/A1/A2 models) controls operation
of amber warning light used during crane operations or while towing disabled
vehicle.
29
YELLOW ABS WARNING LAMP (all models with antilock brake system)
illuminates for three seconds when ignition switch is placed in run position as
ABS is performing self check and then goes out if ABS does not have any
malfunctions.
30
TRAILER AIR SUPPLY VALVE (M931/A1/A2 and M932/A1/A2 models) is
pushed in to supply air to the brake system of towed trailer or semitrailer.
31
EMERGENCY ENGINE STOP CONTROL is pulled out to cut off fuel to
engine. It is used only in an emergency.
32
HEATER BLOWER MOTOR SWITCH activates heater blower.
33
WIPER MOTOR SWITCHES activate and controls speed of wiper.
34
WINDSHIELD WASHER CONTROL sprays cleaning solution on windshield
when depressed.
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