GM Service Manual Online
For 1990-2009 cars only

Bench Inspection Procedure

Tools Required

J 39200 Digital Multimeter

    Important: Perform the following inspection in order to verify operation of a repaired generator:

  1. Mount the generator in a test stand. Ensure that the test stand is capable of driving a generator at 6500 RPM.
  2. Make the connections as shown.
  3. Important: Ensure that the batter is fully charged when making this test.

    Run the engine at 2500 RPM and at ambient temperature.

  4. Slowly increase the generator speed and observe the voltage using J 39200 .
  5. If the voltage is uncontrolled and increases exceeds 16 Volts, repair or replace the generator.
  6. If the voltage is below 16 Volts, perform the following steps:
  7. 5.1. Increase the generator speed.
    5.2. Connect the carbon pile.
    5.3. Adjust the carbon pile in order to obtain maximum amperage output.
    5.4. Maintain 13 Volts or more.
  8. Use and ammeter in order to check the amperage.
  9. • If the output is within 15 Amps of rated output, the generator is good.
    • If the output is not within 15 Amps of rated output, then repair or replace the generator.