GM Full Size Vans 1967-1986 Repair Guide

Alternator

Print

Three basic alternators are used: the 5.5 in. (140mm) Series 1D Delcotron, the 6.2 in. (158mm) Series 150 Delcotron and the integral regulator 10 SI Delcotron.

ALTERNATOR PRECAUTIONS



  1. When installing a battery, ensure that the ground polarity of the battery and the ground polarity of the alternator and the regulator are the same.
  2.  
  3. When connecting a jumper battery, be certain that the correct terminals are connected.
  4.  
  5. When charging, connect the correct charger leads to the battery terminals.
  6.  
  7. Never operate the alternator on an open circuit. Be sure that all connections in the charging circuit are tight.
  8.  
  9. Do not short across or ground any of the terminals on the alternator or regulator.
  10.  
  11. Never polarize an AC system.
  12.  

PRELIMINARY CHARGING SYSTEM TESTS



  1. If you suspect a defect in your charging system, first perform these general checks before going on to more specific tests.
  2.  
  3. Check the condition of the alternator belt and tighten it if necessary.
  4.  
  5. Clean the battery cable connections at the battery. Make sure the connections between the battery wires and the battery clamps are good. Reconnect the negative terminal only and proceed to the next step.
  6.  
  7. With the key off, insert a test light between the positive terminal on the battery and the disconnected positive battery terminal clamp. If the test light comes on, there is a short in the electrical system of the van. The short must be repaired before proceeding. If the light does not come on, proceed to the next step.
  8.  

If the van is equipped with an electric shock, the clock must be disconnected.

  1. Check the charging system wiring for any obvious breaks or shorts.
  2.  
  3. Check the battery to make sure it is fully charged and in good condition.
  4.  

CHARGING SYSTEM OPERATIONAL TEST



You will need a current indicator to perform this test. If the current indicator is to give an accurate reading, the battery cables must be the same gauge and length as the original equipment.

  1. With the engine running and all electrical systems turned off, place a current indicator over the positive battery cable.
  2.  
  3. If a charge of roughly five amps is recorded, the charging system is working. If a draw of about five amps is recorded, the system is not working. The needle moves toward the battery when a charge condition is indicated, and away from the battery when a draw condition is indicated.
  4.  
  5. If a draw is indicated, proceed with further testing. If an excessive charge (10-15 amps) is indicated, the regulator may be at fault.
  6.  

ALTERNATOR OUTPUT TEST



With External Regulator
  1. You will need a tachometer and a voltmeter for this test. You will also need a jumper wire.
  2.  
  3. Connect the tachometer to the engine.
  4.  
  5. Disconnect the wiring harness at the voltage regulator. With a jumper wire, connect the F wire to the number 3 wire in the wire harness plug.
  6.  
  7. Connect a voltmeter across the battery terminals, the positive voltmeter lead to the positive battery terminal and the negative lead to the negative terminal. Note the reading.
  8.  
  9. Start the engine and let it idle.
  10.  
  11. Gradually raise the engine speed to 1,500-2,000 rpm. The reading on the voltmeter should increase 1.0-2.0v over the initial reading. If there is no increase in the reading, the alternator is defective and must be repaired. If the increase is greater than 2v, then the regulator is defective and must be adjusted or replaced. (See voltage adjustment in the regulator section.)
  12.  

With Integral Regulator

  1. You will need an ammeter for this test.
  2.  
  3. Disconnect the battery ground cable.
  4.  
  5. Disconnect the wire from the battery terminal on the alternator.
  6.  
  7. Connect the ammeter negative lead to the battery terminal wire removed in step three, and connect the ammeter positive lead to the battery terminal on the alternator.
  8.  
  9. Reconnect the battery ground cable and turn on all electrical accessories. If the battery is fully charged, disconnect the coil wire and bump the starter a few times to partially discharge it.
  10.  
  11. Start the engine and run it until you obtain a maximum current reading on the ammeter.
  12.  
  13. If the current is not within ten amps of the rated output of the alternator, the alternator is working properly. If the current is not within ten amps, insert a screwdriver in the test hole in the end frame of the alternator and ground the tab in the test hole against the side of the hole.
  14.  
  15. If the current is now within ten amps of the rated output, remove the alternator and have the voltage regulator replaced. If it is still below ten amps of rated output, have the alternator repaired.
  16.  

REMOVAL & INSTALLATION



See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: View of the alternator mounting locations



Click image to see an enlarged view

Fig. Fig. 2: Loosen the alternator pivot bolts to remove the drive belt

  1. Disconnect the battery ground cable to prevent diode damage.
  2.  
  3. Disconnect and tag all wiring to the alternator.
  4.  
  5. Remove the alternator brace bolt.
  6.  
  7. Remove the drive belt.
  8.  
  9. Support the alternator and remove the mounting bolts. Remove the alternator.
  10.  
  11. Install the unit using the reverse procedure of removal. Adjust the belt to have 1 / 2 in. (12.7mm) depression under thumb pressure on its longest run.
  12.  

 
label.common.footer.alt.autozoneLogo