TM-9-2320-272-23-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 1 OF 5
SEPTEMBER 2012
TM-9-2320-272-23-1 - Page 990 of 1313
FIELD MAINTENANCE
INSUFFICIENT BRAKES (VEHICLE STOPPING DISTANCE TOO LONG, NO APPARENT AIR SYSTEM
FAILURE WITH GAUGES AT NORMAL OPERATING PRESSURE, WARNING BUZZER NOT SOUNDING)
INITIAL SETUP:
Tools and Special Tools
Tool Kit, General Mechanic's: Automotive
(Volume 5, WP
0826, Table 1, Item 56)
Gauge, Pressure
(Volume 5, WP
0826, Table 1, Item 19)
Test Set, Electronic Systems
(Volume 5, WP
0826, Table 1, Item 51)
Personnel Required
(2)
References
Point to Point Schematics
Volume 3, WP
0424
References (cont.)
Volume 3, WP
0426
Volume 3, WP
0429
Volume 3, WP
0430
Volume 3, WP
0434
Volume 3, WP
0435
Volume 3, WP
0439
Volume 3, WP
0457
Volume 3, WP
0458
Volume 5, WP
0805
Equipment Condition
Vehicle parked and engine shut down.
(TM
9-2320-272-10)
TROUBLESHOOTING PROCEDURE
INSUFFICIENT BRAKES (VEHICLE STOPPING DISTANCE TOO LONG, NO APPARENT AIR SYSTEM
FAILURE WITH GAUGES AT NORMAL OPERATING PRESSURE, WARNING BUZZER NOT SOUNDING)
NOTE
Conduct these malfunction tests if the vehicle appears to have insufficient brakes and there
is no apparent air system failure. This procedure will check for air leaks in lines, hoses, and
service brake chamber vent lines. Front service brake chamber pressure, service brake
chamber pressure, spring and service brake chamber pressure, limiting valve venting, limiting
valve air delivery pressure, limiting valve air supply pressure, double check valve #1 air supply
pressure, service brake pedal valve primary air system delivery port pressure, primary air
system relay valve pressure, primary air tank to relay valve supply line pressure, secondary
air system relay valve pressure, secondary air tank to relay valve supply line pressure, and
the brake mechanism will also be checked.
TM 9-2320-272-23-1
0120
0120-1
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