ISUZU Amigo/Pick-ups/Rodeo/Trooper 1981-1996

Internal Voltage Regulator

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See Figure 1



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Fig. Fig. 1: Internal voltage regulator assembly

All 6-cylinder vehicles covered in this guide are equipped with alternators having built-in solid state voltage regulators. The regulator is in the end frame (inside) of the alternator. No adjustments are necessary.

TESTING

See Figure 2



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Fig. Fig. 2: Schematic for testing an internal regulator assembly

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the alternator from the vehicle and place on a clean work surface.
  4.  
  5. Connect a variable resistor, two 12V batteries, a fixed resistor and a voltmeter to the regulator.
  6.  
  7. Refer to the illustration and 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 are 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 14.0-14.6 volts. If not, the regulator must be replaced.
  14.  

REMOVAL & INSTALLATION



Except V6 Models
  1. Remove the alternator from the vehicle and place on a clean work surface.
  2.  
  3. Remove the through-bolts and separate the case sections.
  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.  

To install:
  1. Install the diode and brush holder using a new rivet.
  2.  
  3. Solder the connection between the diode L and the brush holder.
  4.  
  5. Install the voltage regulator, diode bridge, condenser, fan guide and nut.
  6.  
  7. Install the stator assembly, and soldering the diode back into place.
  8.  
  9. Connect the BAT terminal, diode and brush hold to the alternator case using the mounting nuts.
  10.  
  11. Attach the alternator sections, and install in the vehicle.
  12.  
  13. Connect the negative battery cable.
  14.  
  15. Start the vehicle and check for proper voltage output.
  16.  

V6 Models

V6 models are equipped with non-serviceable alternators. In the event the regulator fails, the alternator must be removed and replaced.

 
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