Toyota Celica/Supra 1971-1985 Repair Guide

Alternator Repair Guide


See Figures 1, 2 and 3

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Fig. Fig. 1: Exploded view of the common alternator-1971-79 models

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Fig. Fig. 2: Exploded view of the IC type alternator with an external regulator

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Fig. Fig. 3: Exploded view of the IC type alternator with an internal regulator

All Celicas and Supras use a 12 volt alternator. Amperage ratings vary according to the year and model. 1971-79 models utilize a separate, adjustable regulator, while 1980-84 models have a transistorized, nonadjustable regulator, integral with the alternator.


To prevent damage to the alternator and regulator, the following precautionary measures must be taken when working with the electrical system.

  1. Never reverse the battery connections. Always check the battery polarity visually. This is to be done before any connections are made to ensure that all of the connections correspond to the battery ground polarity of the car.
  3. Booster batteries must be connected properly. Make sure the positive cable of the booster battery is connected to the positive terminal of the battery which is getting the boost.
  5. Disconnect the battery cables before using a fast charger; the charger has a tendency to force current through the diodes in the opposite direction for which they were designed.
  7. Never use a fast charger as a booster for starting the car.
  9. Never disconnect the voltage regulator while the engine is running, unless as noted for testing purposes.
  11. Do not ground the alternator output terminal.
  13. Do not operate the alternator on an open circuit with the field energized.
  15. Do not attempt to polarize the alternator.
  17. Disconnect the battery cables and remove the alternator before using an electric arc welder on the car.
  19. Protect the alternator from excessive moisture. If the engine is to be steam cleaned, cover or remove the alternator.


  1. Disconnect the negative battery cable.
  3. Remove the alternator pivot bolt. Push the alternator in and remove the drive belt.
  5. Pull back the rubber boots and disconnect the wiring from the back of the alternator.
  7. Remove the alternator mounting bolt and then withdraw the alternator from its bracket.
  9. Installation is in the reverse order of removal. After installation, adjust the belt tension as detailed in General Information & Maintenance .
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