Alternator Rotor
- Using an ohmmeter, check resistance between both sections of rotor slip rings. Take resistance readings at a minimum of 4 points around the slip rings.
- Resistance should be between 2.9-3.5 ohms on 60-amp rotors, or between 3.0-3.6 ohms on 70-amp rotors. Replace rotor if resistance measured at any point exceeds these values. See Fig 1.