Isuzu Cars and Trucks 1981-1991

Internal Regulator, Except V6

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TESTING
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the alternator from the vehicle.
  4.  
  5. Connect a variable resistor, two 12V batteries, a fixed resistor and a voltmeter to the regulator as shown in the illustration.
  6.  
  7. Measure the voltage V1 across the first battery BAT1. If the reading is between 10 and 13 volts, the battery is normal.
  8.  
  9. Measure the voltage V3 across both the batteries BAT1 and BAT2. If the reading is between 20 and 26 volts, the batteries air normal.
  10.  
  11. Gradually increase the resistance of the variable resistor from zero. Measure the voltage V2. Check to see that the voltage across V1 changes at this time. If there is no change, the voltage regulator is faulty and must be replaced.
  12.  
  13. Measure the voltage at V4 (the voltage across the variable resistor center tap and terminal E with the variable resistor resistance held constant. The measured voltage should be within the specified 14.014.6 volts. If not, the regulator must be replaced.
  14.  



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Fig. Internal voltage regulator test leads internal regulator, except V6 engines

REMOVAL AND INSTALLATION
  1. Remove the alternator from the vehicle.
  2.  
  3. Remove the through bolts and pry case apart.
  4.  
  5. Remove the mounting nuts holding the BAT terminal, the diode and brush holder. Separate the rear cover from the stator.
  6.  
  7. Remove the stator assembly. Cut the diode soldering points, then remove the stator.
  8.  
  9. Remove the nut, fan guide, battery terminal, condenser, diode bridge and voltage regulator. Use a drill press to remove the staked rivet attaching the diode and the brush holder terminal. Break the solder connection between the diode L terminal and the brush holder.
  10.  

 
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