TM-9-2320-279-20-1
M977 SERIES, 8x8 HEAVY EXPANDED MOBILITY TACTICAL TRUCKS (HEMTT)
TECHNICAL MANUAL; MAINTENANCE INSTRUCTIONS; ORGANIZATIONAL MAINTENANCE, VOLUME 1 OF 3
TM-9-2320-279-20-1 - Page 135 of 985
TM
9-2320-279-20-1
Troubleshooting Instructions (Cont)
Figure 2-2 shows location of all circuit breakers to be checked during troubleshooting. Refer 10 it often. Each circuit
breaker is numbered on this illustration.
Figure 2-2. Circuit Breakers (Center Console).
Troubleshooting Index
Tab/e 2-7. System Symptom index
Troubleshooting
Procedure
Page
AIR SYSTEM
1
2
Air pressure buildup slow
................................................................................................................................
2-134
Moisture in air system
......................................................................................................................................
2-137
3
4
Compressor failsto unload
..............................................................................................................................
2-137
Noisy compressor operation
............................................................................................................................
2-138
5.
Compressor cycles constantly .
.........................................................................................................................
6.
Air pressure drops rapidly after engine shutdown
.......................................................................................
2-138
2-139
7.
Compressor leaks oil or coolan
t ..........................
.........................................................................................
8.
Safety valve fails to release system prcssure a
t 150 psi (1034 kPa)
2-14
0
..........................................................
2-139
9.
Air system pressure builds up to more than 130 ps
i (896 kPa
) ..................................................................
2-140
10.
Left or right windshield wiper dots not work .
..............................................................................................
11.
Windshield washer does not work .
.................................................................................................................
2-140
2-141
12.
Air horn does not work
....................................................................................................................................
2-142
13.
Axles wil
l not lock u
p .......................................................................................................................................
14.
Transfer case will not lock up .
.............................................................................
2-143
2-144
15.
Throttle treadle accelerates engine but no air pressure in remainder of air system.
......................................
2-146
ARCTIC HEATER KIT
1.
Coolant pump fail
s to operat
e (indicato
r light does not come on
) ...........................................................
3.
Coolant pump fails to operate (indicator light comes on
)
.........................................................................
Heat output to battery box too low .
...............................................................................................................
4.
Heate
r fail
s to sufficiently warm engin
e (coolant pump operating
)
.........................................................
5.
Circui
t breaker open
s .......................................................................................................................................
DUAL AIR BRAKE SYSTEM
2.
Brakes will not respond properly.
.
..................................................................................................................
Uneven braking
.................................................................................................................................................
3.
Service brakes fail to release or release slowly
.............................................................................................
4.
Brakes grab when applied
................................................................................................................................
5.
Pressure drops over 25 ps
i (172 kPa
) at gage when brakes are applied .
...................................................
6.
Spring brakes will not appl
y ............................................................................................................................
7.
Spring brakes will not releas
e
.........................................................................................................................
2-251
2-253
2-254
2-255
2-256
2-162
2-166
2-168
2-168
2-169
2-169
2-171
Change 2
2-51
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