TM 5-3805-291-23-1
ELECTRICAL SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
0013 00
CHARGING SYSTEM TEST
0013 00
1.
Verify alternator B+ terminal nut is tight and wire has a good connection to B+ terminal (WP 0046 00).
2.
Start engine and set throttle to at least 75 percent. Turn ON all electrical accessories for all test steps below. Allow
engine to run for at least 3 minutes before continuing to step 3. Following table will assist on making calculations during
test.
VOLTAGE
TEST STOP
READING
VOLTAGE SHOULD BE
3
BELOW THIS
4
3 minus 4 =
2.0V
5
6
5 minus 6 =
1.0V
7
1.0V
3.
Measure voltage between alternator B+ terminal and alternator case ground.
4.
Measure voltage across the battery. Put red lead on positive battery terminal and put black lead on negative battery ter-
minal. Step 4 should be completed as quickly as possible after step 3.
Expected Results. Voltage is within 2V of voltage recorded in step 3.
a.
If voltage in step 3 is not more than 2V higher than voltage in step 4, this test is complete and related wiring is cor-
rect at this time. Replace alternator (WP 0046 00).
b.
If voltage in step 3 is more than 2V higher than voltage in step 4, there is high circuit resistance: corrosion, loose
connections, and damaged wiring. Continue to step 5.
5.
Check voltage between machine frame and alternator B+ terminal. Record voltage.
6.
Check voltage between machine frame and positive battery post. Step 6 should be completed as quickly as possible after
step 5.
Expected Results. The voltage difference between step 5 and step 6 does not exceed 1V.
a.
If voltage difference does not exceed tolerance, charging circuit is good. Go to step 7.
b.
If voltage difference exceeds tolerance, there is high resistance in charging circuit: loose cables, corroded cables,
damaged cables, and faulty circuit breaker. Correct problem and retest system.
7.
Check voltage between negative battery post and alternator case ground.
Expected Results. The voltage difference does not exceed 1V.
a.
If voltage difference does not exceed tolerance, ground circuit is good. There is an internal problem with alternator.
Replace alternator (WP 0046 00).
b.
If voltage difference exceeds tolerance, there is high resistance in ground circuit: loose cables, corroded cables,
loose alternator mounting, and poor engine ground. Correct problem and retest system.
