RATTLE/BUZZ FROM I/P (DURING BRAKE APPLY/RELEASE)

Subject: RATTLE/BUZZ FROM INSTRUMENT PANEL DURING BRAKE APPLY/RELEASE

Model and Year: 1990-92 LUMINA 1990-91 LUMINA (APV)

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 91-185-5, DATED FEBRUARY 1991. THE 1990-92 W CAR HAS BEEN ADDED AS WELL AS ADDITIONAL INFORMATION. ALL COPIES OF 91-185-5 SHOULD BE DISCARDED.

Condition:

---------- Some 1990-91 U-vans may experience a rattle or buzz type noise which seems to come from the instrument panel area in front of the driver.

In addition, some 1990-91 'W" cars with J65 brakes and all 1992 "W" cars may experience rattle or buzz type noise which seems to come from the instrument panel area in front of the driver.

Cause: A vibration in the vacuum check valve on the power brake booster.

Correction:

----------- To eliminate this noise, a revised vacuum check valve has been released. This new check valve is on all vehicles built after VIN breakpoints indicated below for the 1990-91 U-vans.

MT119717

For vehicles built prior to these breakpoints and for 1990-92 "W" cars, install a new vacuum check valve and rubber grommet kit, P/N 18018978.

Parts are currently available from GMSPO.

U-Van W-Car ------ ----- Labor Operation Number: H1240 T1812

Use applicable labor time guide for labor hours.

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.