Alternator: Testing and Inspection

Inspection
Rotor
1. Measure the resistance between the slip rings with an ohmmeter.
Specification: 3.5-4.5 Ohms (at 20°C {68°F}
2. If not within specification, replace the rotor.






3. (1)Check continuity between each slip ring and the core with an ohmmeter.
(2)Replace the rotor if there is continuity.
4. Check if the slip ring surface is rough. Use fine sandpaper to repair it if necessary.











Stator
1. Check for continuity between the stator coil leads with an ohmmeter.
2. Replace the stator if there is no continuity.






3. Check continuity between the stator coil leads and the core with an ohmmeter.
4. Replace the stator if there is continuity.











Rectifier
1. Check continuity of the diodes with an ohmmeter.






2. Replace the rectifier if necessary.






Brush
If a brush is worn almost to or beyond the limit, replace the brushes.


Standard: 21.5mm {O.846in}
Minimum: 8.O mm {O.315 in}

Brush spring
1. Measure the force of the brush spring with a spring pres sure gauge.
2. Replace the spring if necessary.


Standard force: 3.1-4.3 N {O.32-0.44 kgf, 0.71-0.96 lbf}
Minimum: 1.6-2.4 N {O.16-0.24 kgf, 0.36-0.52 lbf}

Note: Read the spring pressure with the brush tip projecting 2mm {O.079 in}.






Bearing
1. Check for abnormal noise, looseness, or sticking.
2. Replace the bearing(s) if necessary.