Charging Voltage Inspection
Check the battery condition (see Charging Condition In-
Warm up the engine to obtain actual alternator operating
Check that the ignition switch is turned off, and connect a
tester [A] to the battery terminals [B].
Start the engine, and note the voltage readings at var-
ious engine speeds with the headlight turned on and
then turned off (To turn off the headlight, disconnect
the headlight connector on the headlight unit.).
readings should show nearly battery voltage when the
engine speed is low, and, as the engine speed rises, the
readings should also rise. But they must be kept under
the specified voltage.
Tester (+) to
Turn off the ignition switch to stop the engine, and discon-
nect the tester.
If the charging voltage is kept between the values given in
the table, the charging system is considered to be working
If the charging voltage is much higher than the values
specified in the table, the regulator/rectifier is defective
or the regulator/rectifier leads are loose or open.
If the charging voltage does not rise as the engine speed
increases, then the regulator/rectifier is defective or the
alternator output is insufficient for the loads. Check the
alternator and regulator/rectifier to determine which part
There are three types of alternator failures: short, open
(wire burned out), or loss in rotor magnetism. A short or
open in one of the coil wires will result in either a low output,
or no output at all. A loss in rotor magnetism, which may be
caused by dropping or hitting the alternator, by leaving it
near an electromagnetic field, or just by aging, will result in
Tester (–) to
DC 14.6 ∼ 15 V
ELECTRICAL SYSTEM 16-29