TM-9-2320-272-24-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4
JUNE 1998
TM-9-2320-272-24-1 - Page 181 of 1015
TM 9-2320-272-24-1
ELECTRICAL TROUBLESHOOTING SYMPTOM INDEX
MALFUNCTION
NO.
MALFUNCTION
TROUBLESHOOTlNG
PROCEDURE
PAGE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
ENGINE AND VEHICLE ELECTRICAL SYSTEM
Engine and vehicle electrical system malfunctioning
....................
BATTERY SYSTEM
Batteries are hot, electrolyte is boiling, or excessive use of water.
..........
Specific gravity will not increase to 1.280 under charge
..................
Engine will not crank; some electrical systems inoperative or weak .
.......
All vehicle electrical systems inoperative.
.............................
STARTING SYSTEM
Starter motor inoperative.
.........................................
Solenoid operates, starter operates, but engine cranks slowly.
.............
Starter motor inoperative; no solenoid thump.
.........................
GENERATING SYSTEM
Batteries hot or boiling; correct specific gravity of all cells is 1.280
.........
Batteries use excessive water.
......................................
Batteries run down in service
......................................
No alternator output .
............................................
Alternator output voltage low
......................................
Alternator adjustment
............................................
Battery indicator gauge in red position
...............................
LIGHTING SYSTEM
Lamps will not light.
.............................................
Headlamp (one side) inoperative
....................................
Headlamp (both sides) inoperative.
..................................
Blackout drive or blackout marker light inoperative.
....................
Stoplight inoperative
.............................................
Rear lights inoperative.
...........................................
One or more trailer lights inoperative
................................
DIRECTIONAL SIGNAL SYSTEM
Individual lights do not light with directional signal lever in any position.
...
No lights operate with directional signal control lever in any position .
......
System operates incorrectly in one or more positions of directional
signal control lever.
.............................................
ETHER START SYSTEM
Engine cranks but will not start (fuel available)
........................
INDICATOR, GAUGE, AND WARNING SYSTEM
All gauges inoperative
............................................
One gauge inoperative
............................................
Temperature gauge inoperative (coolant).
.............................
Fuel gauge inoperative.
...........................................
Battery/alternator gauge inoperative.
................................
Horn inoperative
................................................
Low air pressure warning buzzer will not shut off
(air pressure gauges at normal system pressure).
......................
Low air pressure warning buzzer will not shut off and
parking brake warning light flashes with hand/parking
brake in any position (air pressure normal).
..........................
2-95
2-97
2-98
2-98
2-99
2-101
2-103
2-109
2-118
2-120
2-120
2-120
2-123
2-123
2-124
2-125
2-127
2-128
2-130
2-131
2-132
2-133
2-135
2-138
2-140
2-141
2-145
2-149
2-150
2-151
2-153
2-154
2-158
2-161
2-93
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