.Start the engine, and run the engine at the rpm in Table
Note the voltage reading.
Table K 2
the reading is much higher than the values specified
in the table, the regulator/rectifier
defective or its
leads are loose or open. I f the reading does not rise as
the engine speed increases, check the alternator output
and regulator/rectifier (Pg. 21 8) to determine which
part is defective.
The alternator i s made o f a rotor
The stator i s mounted in the alternator cover
the rotor i s secured to the left end o f the crankshaft
and rotates at engine rpm.
Permanent magnets in
the rotor supply the magnetic field for the stator so
that no slip rings or brushes are necessary, making
the alternator practically maintenance free.
has 6 permanent magnets evenly spaced i n
i t s
ference t o generate an alternating current with
per rotor revolution.
about 14.5 V
I f the battery, regulator/rectifier, leads, and connec-
tors are all good, but there i s still low voltage or insuf-
ficient charging current, the alternator may be defective.
There are three types o f alternator failures: short, open
(wire burned out), or loss in rotor magnetism. A short
or open in the coil wire will result in either a low out-
put, or no output at all. A loss in rotor magnetism,
which may be caused by dropping or hitting the rotor,
leaving it near an electromagnetic field, or just by
aging, will result in low output.
Alternator output test
Before starting alternator output test warm up the
engine to obtain actual alternator operating condition.
the engine sprocket cover (Pg. 69), and dis-
connect the yellow leads from the alternator. Set the
multimeter to the 250V AC scale, and connect one
meter leads t o each yellow lead from the alternator.
A. Alternator Leads
4. Alternator Stator
5. Alternator Rotor
6. Wiring Clamp
the engine, run i t at the rpm given in Table
and note the voltage reading. A much lower reading
than that given i n the table indicates that the alternator
i s defective.
Stator coil resistance check
the meter leads from the alternator leads.
the multimeter to the
1 Cl range, and measure
for continuity between the yellow leads.
I f there
more resistance than shown in Table K4, or not meter
reading, the stator has an open and must be replaced.
250 V AC
Reading @4,000 rpm
about 75 V