Repair Pontiac Mid-size 1974-1983 Repair Guide

Alternator

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Fig. Fig. 1 Charging system schematic



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Fig. Fig. 2 Terminal locations on a typical alternator (generator)

The alternating current generator (alternator) supplies a continuous output of electrical energy at all engine speeds. The belt-driven alternator generates electrical energy and recharges the battery by supplying it with electrical current. The alternator consists of four main assemblies: two end frame assemblies, a stator assembly, and a rotor assembly. The rotor assembly is supported in the drive end frame by a ball bearing and at the other end by a roller bearing. These bearings are permanently lubricated and require no maintenance. There are six diodes in the end frame assembly. These diodes are electrical check valves that also change the alternating current developed within the stator windings to direct current (DC) at the output (BAT) terminal. Three of these diodes are negative and are mounted flush with the end frame while the other three are positive and are mounted into a component called a heat sink (which serves as a reservoir for excess heat, thus protecting the alternator). The positive diodes are easily identified as the ones within small cavities or depressions.

No periodic adjustments or maintenance of any kind, except for regular belt adjustments, are required on the entire alternator assembly. Alternator output, in amps, is sometimes stamped on the case of each unit, near the mounting hole. Output ratings of the alternators fitted to engines covered here are 37, 42, 55, 57, 61, 63, 70 and 80 amps. Regulator voltages range between 13.6 and 16 volts at 75°.

ALTERNATOR PRECAUTIONS



To prevent serious damage to the alternator and the rest of the charging system, the following precautions must be observed:

  1. When installing a battery, make sure that the positive cable is connected to the positive terminal and the negative to the negative.
  2.  
  3. When jump-starting the car with another battery, make sure that like terminals are connected. This also applies when using a battery charger.
  4.  
  5. Never operate the alternator with the battery disconnected or otherwise on the uncontrolled open circuit. Double-check to see that all connections are tight.
  6.  
  7. Do not short across or ground any alternator or regulator terminals.
  8.  
  9. Do not try to polarize the alternator.
  10.  
  11. Do not apply full battery voltage to the field (brown) connector.
  12.  
  13. Always disconnect the battery ground cable before disconnecting the alternator lead.
  14.  

REMOVAL & INSTALLATION





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Fig. Fig. 3 Generally, all alternators are mounted in basically the same manner



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Fig. Fig. 4 To remove the alternator, disconnect the battery then pull off the terminal cap



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Fig. Fig. 5 Use a wrench to unfasten the terminal retaining nut ...



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Fig. Fig. 6 ... then remove the terminal connectors from the rear of the alternator



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Fig. Fig. 7 Make sure to unplug all of the alternator electrical connectors



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Fig. Fig. 8 Remove the alternator brace bolt



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Fig. Fig. 9 Use a wrench to loosen ...



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Fig. Fig. 10 ... then remove the alternator mounting bolt



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Fig. Fig. 11 Remove the alternator from the vehicle

  1. Disconnect the battery ground cable to prevent diode damage.
  2.  
  3. Tag and disconnect the alternator wiring.
  4.  
  5. Remove the alternator brace bolt. If the car is equipped with power steering, loosen the pump brace and mount nuts. Detach the drive belt(s).
  6.  
  7. Support the alternator and remove the mount bolt(s). Remove the unit from the vehicle.