Isuzu N-Series. Manual - part 411

6D3-12 CHARGING SYSTEM

2. Check for continuity between each stator coil and

the stator core.

If there is continuity, the stator coils must be re-
placed.

Rectifier, IC Regulator, and Brush Holder As-
sembly

Disassembly

1. Disconnect the IC regulator and the rectifier by

melting the solder connections.

2. Loosen the terminal bolt to remove the rectifier.
3. Disconnect the IC regulator, the brush holder, and

the condenser by melting the solder connections.

4. Remove the IC regulator from the terminal plates.

5. Remove the stud bolts from the terminal plate.

Notice:
If the brushed, brush holder, and the condenser to be re-
used, do not remove the stud bolts.

6. Remove the brush holder from the terminal plate.

Inspection

1. Brush

Each brush has a line to indicate whether or not the
brush is serviceable.

If the line is not visible, the brush must be replaced.

2. Rectifier

Resistance Between The 
Coil End “N” And The Each 
Coil Ends (Reference)

ohms

Standard

0.17

N6A1056E

N6A1050E

Brush Length (Reference)

mm (in)

Standard

Limit

25 (0.984)

6 (0.236)

N6A1058E

N6A1059E

CHARGING SYSTEM 6D3-13

1) Check for continuity with a circuit tester be-

tween the battery and each of the three stator
coil lead terminals.
If there is continuity from battery to each of the
three stator coil lead terminals, the rectifier is
normal.
If there is no continuity, the rectifier must be re-
placed.
Check for continuity with a circuit tester be-
tween the earth and each of the three stator coil
lead terminals.
If there is continuity from each of the three sta-
tor coil lead terminals to earth, the rectifier is
normal.
If there is no continuity, the rectifier must be re-
placed.

2) Reverse the polarity of the test probes.

If there is no continuity, the rectifier is normal.
If there is continuity, the rectifier must be re-
placed.

3. IC Regulator

The IC regulator may be tested with either a circuit
tester or pair of standard voltmeters.
Refer to the illustration.
1) Circuit tester (or voltmeter) range is from 0 —

50 volts in 0.5 volt increments.

2) Two twelve volt batteries are required.
3) Note the variable resistor.
4) This resistor is rated at 100 watts/3 ohms.

4. Testing the IC Regulator

Refer to the wiring diagram when testing the IC
regulator.
1) Connect the batteries in series.
2) Measure the battery power (voltage).

3) Connect the circuit tester (1) (or voltmeter V2)

as shown in the illustration.

4) Set the variable resistor (3) to zero.
5) Slowly increase the resistance of the variable

resistor toward the build-up point.
Measure the voltage between E and F.
As long as the resistance is below the build-up
point, the voltage reading should be stable and
less than two volts.
When the resistance exceeds the build-up
point, the voltage reading should be two volts or
greater.
If the voltage does not exceed two volts after
reaching the build-up point, the IC regulator
must be replaced.

6) Return the variable resistor (3) to zero.
7) Connect the circuit tester (or voltmeter V1) as

shown in the illustration.

8) Measure the voltage at terminals S, L, and E.
9) Slowly increase the resistance of the variable

resistor.

N6A1060E

N6A1061E

Battery Power

V

28 — 29

N6A1062E

6D3-14 CHARGING SYSTEM

Note the point at which the voltage quickly
builds up to between 2 and 6 volts.
This will indicate the point at which the voltage
regulator begins to function.
If the measured voltage is outside the specified
range, the voltage regulator must be replaced.

10) Repeat Steps 3 through 5 to measure the volt-

age between terminals B, L, and E.

Refer to the wiring diagram.
The regulator voltage should be between 0.5
and 3 volts higher than the measured voltage.
If the regulator voltage is outside this range, the
voltage regulator must be replaced.

Reassembly

1. Install the brush holder and the stud bolts to the ter-

minal plate.
Check that the stud bolts fit properly.

2. Attach the IC regulator to the terminal plate.
3. Solder the IC regulator, the brush holder and the

condenser.

Take care not to heat the IC regulator.
Over-heating will resulting damage to the IC regu-
lator.

4. Set the rectifier to the IC regulator assembly.
5. Solder rectifier and IC regulator.

Take care not to heat the IC regulator.
Over-heating will resulting damage to the rectifiers
and the IC regulator.

6. Tighten the rectifier terminal bolt.

Oil Seal

Check the rear cover oil seal bore for oil leakage.
Oil Seal Replacement

1. Use a screwdriver to remove the oil seal from the

rear cover side.
Take care not to damage the oil seal bore.

2. Discard the used oil seal.
3. Use the oil seal installer to install the new oil seal.

N6A1063E

N6A1050E

Legend

1. Oil seal installer
2. Oil seal

N6A1065E

CHARGING SYSTEM 6D3-15

Vacuum Pump

Disassembly

1. Remove the center plate from the vacuum pump

housing.

2. Remove the vacuum pump rotor and the vanes

from the housing.

Inspection and Repair

1. Vacuum Pump Housing and Center Plate

Inspect the vacuum pump housing and the center
plate for excessive wear, abrasion, and scoring.
If any of these conditions are present, the vacuum
pump housing and center plate must be replaced.
Inspect the vacuum pump housing inside for wear
and damage.
If the measured inside diameter is outside the
specified range, replace the vacuum pump hous-
ing.

2. Vane

Inspect the vanes for excessive wear and damage.
Replace all four vanes if either of these conditions
are present.
Never replace only one vane.

3. Rotor

1) Inspect the rotor for excessive wear, abrasion,

and scoring.
Pay particular attention to the internal spline.
Replace the rotor if any of these conditions are
present.

2) Inspect the generator rotor shaft splines for

backlash.
Replace the rotor if backlash is present.

4. Check Valve

1) Carefully force the valve from the “B” side as

shown in the illustration.

N6A1066E

N6A1067E

Vacuum Pump Housing 
Inside Diameter (Reference)

mm (in)

Standard

69.5 — 69.6 (2.736 — 

2.740)

Vane Length (Reference)

mm (in)

Standard

18.0 (0.709)

N6A1068E