1981 Plymouth Champ LS, Automatic TransFACTORY OEM SERVICE PROCEDURE

Field Coil Draw

  1. On 100 ampere alternator, connect a jumper wire between field terminal of alternator and positive terminal of a fully charged battery. Connect test ammeter positive lead to other field terminal of alternator, and the negative lead to battery negative terminal.
  2. On other alternators, connect jumper wire between field terminal of alternator and negative terminal of a fully charged battery. Connect test ammeter positive lead to other field terminal of alternator and negative lead to battery positive terminal. Then connect jumper wire between alternator end shield and battery negative terminal.
  3. With alternator on an insulated surface, slowly rotate alternator rotor by hand. Observe ammeter reading. Field coil draw should be 4.75-6.0 amps. (100 amp.) or 4.5-6.5 amps. (all others) at 12 volts.
  4. A low rotor coil draw indicates high resistance in field coil circuit (brushes, slip rings or rotor coil). A high rotor coil draw indicates possible shorted rotor coil or grounded rotor. No reading indicates an open rotor or defective brushes.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.