TM 5-3810-289-12
Section XI. MAINTENANCE OF ELECTRICAL SYSTEM COMPONENTS
continuity check of electrical circuit. Repair or replace
4-35.
Alternator Assembly Service, Test, and
defective wiring or terminals.
Replacement
(2) Negative heat sink-rectifier test (fig. 4-
a
General.
(1) The self-rectifying charging alternator
(a) The negative heat sink is
is designed to give long life and satisfactory service with
grounded to the housing by means of its mounting
a minimum amount of maintenance, but the following
screws and stud. Be sure that these screws are clean
precautions must be observed.
and tight so that the negative heat sink makes good
contact with the housing.
Caution: Do not make, or break, any
(b) Correct the negative lead of an
alternator connections while alternator is operation
ohmmeter to check point one and touch the positive lead
This would damage the voltage regulator.
to terminals 4, 5, and 6. A high resistance reading
should be obtained. If a low resistance reading is
Caution: Never operate alternator without
obtained the diode is shorted. Replace the alternator.
battery being connected in circuit.
c. Alternator Replacement. Refer to figure 4-
25 and replace the alternator.
Caution: When charging batteries from an
d. Alternator Belt Replacement.
external source of power, be sure battery is
(1) Refer to figure 3-9 and replace the
connected from circuit before beginning charging
alternator belt.
operation, to prevent damage to alternator rectifying
(2) Refer to figure 4-20 and adjust
alternator belt.
(2) Before removing alternator for repair
4-36.
Reverse Current Polarity Protective Relay
replacement, inspect the drive belt, mounting brackets,
a. General. Since alternators are sensitive to
and wiring harness, in the following manner:
electric current polarity, incorrect wiring will cause the
(a) Check belts for proper tension,
diodes in the alternator to short out. To protect against
excess wear, or the presence of oil or grease which
this, a reverse current polarity protective relay is installed
could cause them to slip.
in the engine electrical system (fig. 1-4).
(b) Check pulleys for discoloration
b. Removal.
which could indicate overheating due to belt slippage.
(1) Disconnect the three cannon-plug-type
Inspect pulleys for wear which could allow belts to
electrical connections to the reverse polarity relay.
bottom in the pulley grooves. Replace worn or defective
(2) Remove the two mounting capscrews
parts.
and lockwashers and remove the protective relay.
(c) Check mounting brackets and
c. Installation.
Installation is reversed of
tension adjusting arm. Wear or looseness of these parts
removal procedures.
will prevent proper belt adjustment and may result in
misalignment which will cause premature wear on belts,
4-37.
Starting
Motor
Service,
Test
and
pulleys, and bearings.
Tighten replace parts as
Replacement
necessary.
a. Removal and Installation. Refer to figure 4-
(d) Inspect all wiring and terminals for
27 to remove or install the starting motor.
signs of wear, looseness, or corrosion. Check for worn
b. Service.
or frayed insulation which could result in shorts or
(1) At installation, add two or three drops
grounds. Clean and tighten all terminal connections.
of OE-30 lubricating oil in each oil reservoir.
(e) Check batteries. Take a specific
(2) Every 200 hours add at least 3 to 5
gravity reading on each cell. Replace batteries which
drops of OE-30 lubrication oil in each oil reservoir.
indicate one or more defective cells.
b. On-Equipment Test.
4-32
