Description & Operation

This article covers service and repair of conventional brake system components. All models are equipped with front disc brakes. Rear brakes may be either disc or drum. Master cylinder has a fluid level sensor. Proportioning valves are integral to master cylinder on non-ABS vehicles. On ABS equipped vehicles, proportioning valves are located in rear brake lines. 2001 Grand Prix and Century, Regal are not equipped with proportioning valves. Hydraulic brakeline routing is diagonally split from left front to right rear, and right front to left rear. Anti-Lock Brake System (ABS) is optional on all models.

Three cable operated parking brake systems are used. Drum brakes use a lever to engage rear brake shoes. Rear disc brakes use either calipers to engage brake pads, or engages brake shoes located in hub of rear disc rotors. All applications use push-to-release parking brake pedal mechanism (no release handle).

On all vehicles, BRAKE warning light comes on when one or more of the following conditions exist:

Parking brake is applied or not fully released.
Fluid level in master cylinder reservoir is low.
During engine cranking. A bulb check is performed to indicate that the warning circuit is operational.

NOTE: For diagnosis and repair of ABS related problems, see appropriate ANTI-LOCK article.

Applying the parking brake causes the external caliper parking brake lever to move and rotate a spindle within the caliper housing. As the spindle rotates, a connecting rod is pushed against an internal adjusting screw that is threaded into a sleeve nut (cone) in the piston. This causes the piston to move outward bringing the inboard brake pads against the rotor. When the inboard brake pad contacts the rotor, a reaction force causes the caliper housing to slide inward, pressing the outboard brake pads against the rotor. This piston contains a self-adjusting mechanism that keeps the parking brake in proper adjustment. As the pads wear, the piston moves through the seal to maintain proper pad to rotor clearance. The park brake adjusts to the proper clearances through an internal sleeve nut that rotates and moves as one unit with the piston.