Bench Testing: Rotor
- Place ohmmeter on lowest scale. Connect ohmmeter across slip rings. For resistance values, see ROTOR RESISTANCE table.
ROTOR RESISTANCE
| Alternator |
Ohms |
| 90-amp |
2.6 - 3.2 |
| 115-amp |
2.4 - 2.9 |
- If resistance is too low, rotor has short circuit and must be replaced. If resistance is infinity (no continuity), rotor has open circuit and must be replaced.
- Place ohmmeter on x1000 scale. Connect ohmmeter between either slip ring and rotor core. No continuity should exist. If continuity exists, rotor is grounded and must be replaced.