TM 5-3805-290-23-1
ELECTRICAL SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
0013 00
ELECTRIC STARTING SYSTEM TEST - CONTINUED
CAU T I ON
Do not crank engine for more than 30 seconds. Allow starter to cool for two minutes before cranking again.
Never turn disconnect switch off while engine is running. Serious damage to electrical system can result.
If starting motor does not crank or cranks slowly, perform the following procedure.
1.
Measure voltage of battery. Measure voltage across battery posts with multimeter when cranking or attempting to crank
engine. Do not measure voltage across cable post clamps.
a.
If voltage is equal or greater than voltage specified in Table 2, proceed to step 2.
b.
If battery voltage is less than voltage specified in Table 3, low charge in battery can be caused by several condi-
tions: battery deterioration, shorted starting motor, faulty alternator, loose drive belts, or current leakage in another
part of electrical system. Refer to TM 9-6140-200-14, Operator's, Unit and Direct Support and General Mainte-
nance Manual for Lead-Acid Storage Batteries to test battery.
2.
Measure current sent to starting motor solenoid from positive post of battery.
N OT E
If these conditions exist, DO NOT perform test in step 3 because starting motor has problem:
a. Voltage at battery post is within 2V of lowest value in applicable temperature range of Table 3.
b. Large starting motor cables get hot.
a.
Use ammeter to measure current. Place jaws of ammeter around cable connected to battery terminal. Amperage
should be no more than 85 Amps at 18V.
b.
Current and voltages are measured at temperature of 80F (27C). When temperature is below 80F (27C), volt-
age will be lower through starting motor. When temperature is below 80F (27C), current through starting motor
will be higher. If current is too great, problem exists in starting motor. Replace starting motor (WP 0048 00).
c.
If current is within specification, proceed to step 3.
3.
Use multimeter to measure voltage of starting motor while cranking or attempting to crank engine.
a.
If voltage is equal or greater than voltage given in Table 3, battery and starting motor cable to starting motor are
within specifications. Proceed to step 5.
b.
If starting motor voltage is less than voltage specified in Table 3, voltage drop between battery and starting motor
is too great. Proceed to step 4.
4.
Measure voltage drops in cranking circuits with multimeter. Compare results with voltage drops allowed in Table 3.
a.
Voltage drops are equal to or less than voltage drops given in Table 3. Proceed to step 5 to check engine.
b.
Voltage drops are greater than voltage drops given in Table 3. Replace wire in question (WP 0079 00).
5.
Rotate crankshaft by hand to ensure crankshaft is not stuck.
a.
If crankshaft is stuck or difficult to turn, proceed to step 6.
b.
If engine is not difficult to turn, replace starter (WP 0048 00).
6.
Check oil viscosity.
a.
Pull oil level gage and determine if oil is dirty (TM 5-3805-290-10).
b.
Refer to PMCS (WP 0020 00) to determine if correct grade oil was used for current climate.
c.
If oil is dirty or incorrect grade, change engine oil and filter (WP 0025 00).
d.
If problem still exists go to step 7.
0013 00-27
