Alternator: Testing and Inspection

Rotor




1. Measure resistance between slip rings with a ohmmeter. If it is not within standard resistance, replace rotor.

Standard resistance: 3.5 - 4.5 ohm

2. Check for continuity between slip ring and core with a circuit tester. Replace rotor if there is continuity.




3. If slip ring surface is rough, smooth with a lathe or fine sandpaper.

Stator

1. Check for continuity between stator coil leads with a circuit tester.







2. Replace stator if there is no continuity.
3. Check for continuity between stator coil leads and core with a circuit tester.
4. Replace stator if there is continuity.

Rectifier




1. Check for continuity between each diode with an ohmmeter.







2. Replace if necessary.

Brush





If brushes are worn to, or beyond limit, replace them.

Standard: 0.85 in (21.5 mm)
Minimum: 0.32 in (8.0 mm)

Brush spring
1. Measure force of brush spring with a spring pressure gauge.





2. Replace the spring if necessary.

Standard force: 0.71 - 0.93 lb-ft (3.1 - 4.1 N.m, 0.32 - 0.42 kg-m)

Minimum: 0.36 - 0.52 lb-ft (1.60 - 2.4 N.m, 0.16 - 0.24 kg-m)

Read spring pressure with brush tip projecting 0.08 in (2 mm).

Bearing

1. Check for abnormal noise, looseness, insufficient lubrication, etc.




2. Replace bearing(s) if there is any abnormality.