2004 GMC Envoy Owner's Manual - Page 349

Brake Wear Your vehicle has four-wheel disc brakes. Disc brake pads have built-in wear indicators that make a high-pitched warning sound when the brake pads are worn and new pads are needed. The sound may come and go or be heard all the time your vehicle is moving (except when you are pushing on the brake pedal firmly). Properly torqued wheel nuts are necessary to help prevent brake pulsation. When tires are rotated, inspect brake pads for wear and evenly tighten wheel nuts in the proper sequence to GM torque specifications. Brake linings should always be replaced as complete axle sets. Brake Pedal Travel See your dealer if the brake pedal does not return to normal height, or if there is a rapid increase in pedal travel. This could be a sign of brake trouble. {CAUTION: The brake wear warning sound means that soon your brakes will not work well. That could lead to an accident. When you hear the brake wear warning sound, have your vehicle serviced. Notice: Continuing to drive with worn-out brake pads could result in costly brake repair. Some driving conditions or climates may cause a brake squeal when the brakes are first applied or lightly applied. This does not mean something is wrong with your brakes. Brake Adjustment Every time you make a brake stop, your disc brakes adjust for wear. 5-41