Interior - Rattle/Buzz From I/P During Braking

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NUMBER: 92-T-38

CORP.REF.NO: 135001R

DATE: February 1992

SECTION: 5


SUBJECT:
RATTLE/BUZZ FROM INSTRUMENT PANEL DURING BRAKE APPLY/RELEASE
- INSTALL NEW VACUUM CHECK VALVE

MODELS/YEARS:
1990-91 SILHOUETTE AND 1988-92 CUTLASS SUPREME


This bulletin cancels and replaces Dealer Technical Bulletin 91-T-59 which should be discarded.

CONDITION:
Some 1990-91 Silhouettes may exhibit a rattle or buzz type noise which seems to come from the instrument panel area in front of the driver. In addition, some 1988-91 Cutlass Supreme with J65 brakes and all 1992 Cutlass Supremes may exhibit a 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 Silhouettes built after vehicle number MT305086.

For Silhouettes built prior to this breakpoint, and for 1988-92 Cutlass Supremes, install a new vacuum check valve and rubber grommet kit, P/N 18018978, which is currently available from GMSPO.