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Service bulletin 4540

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id10023732
Published by NHTSA2008-01-29
Manufacturer's number4540
Manufacturer's date2008-06-01
ReplacesPIT4540A
NHTSA componentSERVICE BRAKES, HYDRAULIC:FOUNDATION COMPONENTS:MASTER CYLINDER; SERVICE BRAKES, AIR

NHTSA's summary

VEHICLE SHAKES OR VIBRATES AT HIGHWAY SPEEDS. *NJ UPDATED 8/25/08. *PE

The document

No address for NHTSA's copy can be built for this communication. Ask the dealer for it by the manufacturer's number.

Components

Brakes, Brake master cylinder

Vehicles listed
BUICK RAINIER2007
CHEVROLET TRAILBLAZER2008
CHEVROLET TRAILBLAZER 3602007 (the catalog's model; the bulletin names a series or trim of it)
GMC ENVOY2008
GMC ENVOY 3602007 (the catalog's model; the bulletin names a series or trim of it)
SAAB 9-7X2007, 2008

Listing a model year does not mean every vehicle of it is concerned: the document says which.