Subaru Legacy III (2000-2003 year). Manual - part 96

SC(H4SO)-18

STARTING/CHARGING SYSTEMS

GENERATOR

E: INSPECTION

1. DIODE

CAUTION:
Never use a mega tester (measuring use for 
high voltage) or any other similar measure for 
this test; otherwise, the diodes may be dam-
aged.
1) Checking positive diode
Check for continuity between the diode lead and
positive side heat sink. The positive diode is in
good condition if resistance is 1 

Ω

 or less only in the

direction from the diode lead to heat sink.

2) Checking negative diode
Check for continuity between the negative side
heat sink and diode lead. The negative diode is in
good condition if resistance is 1 

Ω

 or less only in the

direction from the heat sink to diode lead.

2. ROTOR

1) Slip ring surface
Inspect the slip rings for contamination or any
roughness of the sliding surface. Repair the slip
ring surface using a lathe or sand paper.
2) Slip ring outer diameter
Measure the slip ring outer diameter. If the slip ring
is worn replace rotor assembly.

Slip ring outer diameter:

Standard

22.7 mm (0.894 in)

Limit

22.1 mm (0.870 in)

3) Continuity test
Check the resistance between slip rings using cir-
cuit tester.
If the resistance is not within specification, replace
the rotor assembly.

Specified resistance:

Approx. 1.8 — 2.2 

Ω

Ω

Ω

Ω

4) Insulation test
Check the continuity between slip ring and rotor
core or shaft. If resistance is 1 

Ω

 or less, the rotor

coil is grounded, and so replace the rotor assem-
bly.

5) Ball bearing (rear side)
Check the rear ball bearing. Replace if it is noisy or
if the rotor does not turn smoothly.

(A) Diode lead

(B) Heat sink (Positive side)

(A) Diode lead

(B) Heat sink (Negative side)

( A )

( B )

SC-00042

SC-00043

( A )

( B )

SC-00044

SC-00045

SC(H4SO)-19

STARTING/CHARGING SYSTEMS

GENERATOR

3. STATOR

1) Continuity test
Inspect the stator coil for continuity between each
end of the lead wires. If resistance is 1 M 

Ω

 or

more, the lead wire is broken, and so replace the
stator assembly.

2) Insulation test
Inspect the stator coil for continuity between stator
core and each end of lead wire. If resistance is 1 

Ω

or less, the stator coil is grounded, and so replace
the stator assembly.

4. BRUSH

1) Measure the length of each brush. If wear ex-
ceeds the service limit, replace the brush. Each
brush has the service limit mark (A) on it.

Brush length:

Standard

18.5 mm (0.728 in)

Service limit

5.0 mm (0.197 in)

2) Checking brush spring for proper pressure
Using a spring pressure indicator, push the brush
into the brush holder until its tip protrudes 2 mm
(0.08 in). Then measure the pressure of brush
spring. If the pressure is less than 2.2 N (224 g,
7.91 oz), replace the brush spring with a new one.
The new spring must have a pressure of 4.8 to 6.0
N (489 to 612 g, 17.26 to 21.60 oz).

5. BEARING (FRONT SIDE)

Check the front ball bearing. If the resistance is felt
while rotating, or if abnormal noise is heard, re-
place the ball bearing.

(A) Stator

( A )

SC-00047

SC-00048

18.5

(0.728)

(0.197)

5.0

SC-00162

( A )

SC-00093

SC(H4SO)-20

STARTING/CHARGING SYSTEMS

BATTERY

4. Battery

A: REMOVAL

1) Remove battery cable holder (A) from battery
rod.

2) Disconnect the positive (+) cable after discon-
necting the negative (

−

) cable of battery.

3) Remove flange nuts from battery rods and take
off battery holder.

4) Remove battery.

B: INSTALLATION

Install in the reverse order of removal.

Tightening torque:

3.4 N·m (0.35 kgf-m, 2.5 ft-lb)

NOTE:
• Clean battery cable terminals and apply grease
to prevent corrosion.
• Connect the positive (+) cable of battery and then
the negative (

−

) cable of the battery.

C: INSPECTION

WARNING:
• Electrolyte has toxicity; be careful handling
the fluid.
• Avoid contact with skin, eyes or clothing. Es-
pecially at contact with eyes, flush with water
for 15 minutes and get prompt medical atten-
tion.
• Batteries produce explosive gases. Keep
sparks, flame, cigarettes away.
• Ventilate when charging or using in enclosed
space.

• For safety, in case an explosion does occur,
wear eye protection or shield your eyes when
working near any battery. Never lean over a bat-
tery.
• Do not let battery fluid contact eyes, skin,
fabrics, or paint-work because battery fluid is
corrosive acid.
• To lessen the risk of sparks, remove rings,
metal watch-bands, and other metal jewelry.
Never allow metal tools to contact the positive
battery terminal and anything connected to it
while you are at the same time in contact with
any other metallic portion of the vehicle be-
cause a short circuit will be caused.

1. EXTERNAL PARTS:

Check for the existence of dirt or cracks on the bat-
tery case, top cover, vent plugs, and terminal posts.
If necessary, clean with water and wipe with a dry
cloth.
Apply a thin coat of grease on the terminal posts to
prevent corrosion.

2. ELECTROLYTE LEVEL:

Check the electrolyte level in each cell. If the level
is below MIN LEVEL, bring the level to MAX LEVEL
by pouring distilled water into the battery cell. Do
not fill beyond MAX LEVEL.

3. SPECIFIC GRAVITY OF ELECTROLYTE:

1) Measure specific gravity of electrolyte using a
hydrometer and a thermometer.
Specific gravity varies with temperature of electro-
lyte so that it must be corrected at 20

°

C (68

°

F) us-

ing the following equation:

S

20

 = St + 0.0007 

××××

 (t 

−−−−

 20)

S

20

: Specific gravity corrected at electro-

lyte temperature of 20

°°°°

C

St : Measured specific gravity
t : Measured temperature (

°°°°

C)

Determine whether or not battery must be 
charged, according to corrected specific 
gravity.
Standard specific gravity: 1.220 — 1.290 [at 
20

°°°°

C (68

°°°°

F)]

SC-00139

( A )

SC-00053

SC-00094

1.28

Specific gravity [20

˚C (68

˚F)]

Specific gravity and state of charge

Complete charge

Charging condition

1.26

1.24

1.22

1.20

1.18

1.16

1.14

1.12

100%

75% 50%

22%

0%

(%)

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STARTING/CHARGING SYSTEMS

BATTERY

2) Measuring the specific gravity of the electrolyte
in the battery will disclose the state of charge of the
battery. The relation between the specific gravity
and the state of charge is as shown in figure.

D: MEASUREMENT

WARNING:
• Do not bring an open flame close to the bat-
tery at this time.

CAUTION:
• Prior to charging, corroded terminals should
be cleaned with a brush and common baking
soda solution.
• Be careful since battery electrolyte overflows
while charging the battery.
• Observe instructions when handling battery
charger.
• Before charging the battery on vehicle, dis-
connect battery ground terminal. Failure to fol-
low this rule may damage alternator's diodes or
other electrical units.

1. JUDGMENT OF BATTERY IN CHARGED 
CONDITION

1) Specific gravity of electrolyte is held at a specific
value in a range from 1.250 to 1.290 for more than
one hour.
2) Voltage per battery cell is held at a specific value
in a range from 2.5 to 2.8 volts for more than one
hour.

2. CHECK HYDROMETER FOR STATE OF 
CHARGE

3. NORMAL CHARGING

Charge the battery at current value specified by
manufacturer or at approximately 1/10 of battery's
ampere-hour rating.

4. QUICK CHARGING

Quick charging is a method in which the battery is
charged in a short period of time with a relatively
large current by using a quick charger.
Since a large current flow raises electrolyte temper-
ature, the battery is subject to damage if the large
current is used for prolonged time. For this reason,
the quick charging must be carried out within a cur-
rent range that will not increase the electrolyte tem-
perature above 40

°

C (104

°

F).

It should be also remembered that the quick charg-
ing is a temporary means to bring battery voltage
up to a fair value and, as a rule, a battery should be
charged slowly with a low current.

CAUTION:
• Observe the items in 3. NORMAL CHARGING.
• Never use more than 10 amperes when
charging the battery because that will shorten
battery life.

Hydrometer 

indicator

State of charge 

Required action

Green dot

Above 65%

Load test

Dark dot

Below 65%

Charge battery

Clear dot

Low electrolyte

Replace battery* 

(If cranking complaint)

*: Check electrical system before replacement.