damage to the alternator and regulator, the following precautionary
measures must be taken when working with the electrical system.
NEVER reverse the battery connections. Always check the battery
polarity visually. This is to be done before any connections are made to
ensure that all of the connections correspond to the battery ground
polarity of the car.
Booster batteries must be connected properly. Make sure the
positive cable of the booster battery is connected to the positive
terminal of the battery which is getting the boost.
Disconnect the battery cables before using a fast charger; the
charger has a tendency to force current through the diodes in the
opposite direction for which they were designed.
NEVER use a fast charger as a booster for starting the car.
NEVER disconnect the voltage regulator while the engine is
running, unless as noted for testing purposes.
Do NOT ground the alternator output terminal.
Do NOT operate the alternator on an open circuit with the field
Do NOT attempt to polarize the alternator.
Disconnect the battery cables and remove the alternator before
using an electric arc welder on the car.
Protect the alternator from excessive moisture. If the engine is
to be steam cleaned, cover or remove the alternator.
TESTINGThere are several checks that
can be done with inexpensive equipment. The first thing to do is to see
if the discharge warning light on the dashboard lights when the
ignition switch is turned on. If it is not lit, check for blown fuses, a
blown out bulb itself (The system will not charge with a bad bulb) or
If the warning light does light with the ignition
switch on, but stays on with the engine running, check for a loose (or
missing) belt, a loose or faulty battery cable, corrosion, a blown fuse
or fusible link or a shorted or open wire.
If everything seems to
be good (including the battery), but the charge light is always on, then
the alternator itself probably is to blame. This does not mean the
whole alternator needs to be replaced. Many times, the IC regulator can
become faulty and cause the no-charge condition. There is a way to
determine whether just the IC regulator or the whole alternator should
The alternator can be "full-fielded;" that is, the F
terminal can be shorted to ground, making the alternator think there is a
heavy load on the electrical system. If the alternator starts putting
out when the F terminal is shorted to ground, then the IC regulator is
probably faulty. If the alternator still does not put out when the F
terminal is grounded, then the whole alternator should probably be
replaced. It can be concluded that the alternator is "putting out" by
observing the voltage of the battery. The system is charging when the
battery voltage is approximately 14-15 volts. If it is only 12-12.5
volts, something is wrong. If the charging voltage is too high (more
than 15 volts, the battery smells like sulfur or frequently runs out of
water or the bulbs in the vehicle burn out too frequently, then the IC
regulator is probably faulty (See Regulator).
Check the alternator
and IC regulator by performing the following:
Fig. 1 Checking the alternator and IC regulator 2S-E, 3S-FE
and 3S-GE engines shown
Fig. 2 Checking the alternator and IC regulator 4A-FE, 5S-FE
and 3S-GTE engines shown
Ground the F terminal on the alternator.
Start the engine.
Analyze the voltage, using the information above.
Hope this help (remember rated this).