GM Service Manual Online
For 1990-2009 cars only

Noise from a generator may be caused by any of the following:

    • A loose drive pulley
    • Loose mounting bolts
    • Worn or dirty bearings
    • A defective diode
    • A worn stator

A high frequency whine or magnetic noise may be heard at full output. This is a normal condition. Perform a generator output test in order to help distinguish bearing noise from magnetic noise or whine. Refer to Generator Not Operating Properly .

A growling noise under a high load condition could indicate a shorted bridge diode. A generator with a shorted diode will also have a reduced output. Perform a generator output test. Refer to Generator Not Operating Properly

It is also helpful to listen to the generator under a moderate load (i.e. headlights ON) in order to determine if there is a bearing or magnetic noise.

Do not disassemble the CS 130D generator. Generator service is limited to replacement only. Refer to Generator Replacement .