GENERATOR WHINE INSTALL NEW STYLE ROTOR

MODELS AFFECTED: 1988 ELDORADOS AND SEVILLES

Some 1988 Eldorados and Sevilles may exhibit generator whine noise at idle or at rpm levels just above idle. The noise is worse at high electric loads or with a low battery. The noise may be caused by a vibration that occurs in the stator of the high output CS 144 generator. To reduce the level of magnetic noise output, a new rotor assembly is available.

To reduce generator noise, perform the following procedure:

1. Verify that the noise is generator magnetic whine. With the engine running and noise present, disable the generator by grounding the green generator test lead underhood, or by disconnecting the generator weatherpak connector.

Injector noise, generator bearing or air noise, and noise from other underhood sources can sometimes sound like generator magnetic whine.

2. If the noise goes away with the generator disabled, check to be sure that the generator does not already have the new rotor assembly by verifying part numbers.

NOTE: Some magnetic whine noise is normal in the high output 120 amp CS 144, especially during high current output. The noise does not indicate mechanical or electrical conditions inside the generator. There is currently no service fix for "noisy" generators which are already equipped with the new style rotor.

3. If the vehicle has an old style rotor, replace the rotor and drive end frame assembly with P/N 10456386, which is currently available from GMSPO.

NOTE: Do not apply the new rotor to past model vehicles. The new rotor reduces output at idle. Higher idle current draws in 1987 vehicles may result in reduced battery life.

4. Reassemble and check charging system for proper operation.

NOTE: Installing the new rotor assembly will reduce charging system output at idle by about 5 amps. This is a normal condition.

For warranty purposes use Labor Operation T6327 at 1.0 hour.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.