1998 Oldsmobile Aurora Brake Service (ONLINE REPAIR MANUALS)

System Operation

The purpose of the anti-lock brake system is to prevent wheel lock-up under heavy braking conditions on virtually any road surface. When a wheel locking condition exists, the Pressure Modulator Valve (PMV) assembly isolates each wheel's hydraulic circuit, then begins modulation of fluid pressure according to wheel speed inputs to the Electronic Brake Control Module (EBCM) or Electronic Brake and Traction Control Module (EBTCM). The PMV is controlled by the EBCM.

Modulation occurs by means of three ABS modes: pressure hold, pressure reduce and pressure increase. The PM...

The caliper assembly, Fig. , has a single bore and is mounted to the support bracket with two mounting bolt and sleeve assemblies. Hydraulic pressure created by applying the brake pedal, is converted by the caliper to a stopping force. This force acts equally against the piston and the bottom of the piston bore to move the piston outward and to slide the caliper inward resulting in a clamping action. This clamping action presses the linings against the rotor, creating friction to stop the vehicle.

When the parking brake is applied, the external caliper parking brake lever moves and r...

Master Cylinder Overhaul

Except Aurora, Bonneville, Eighty-Eight, LeSabre, LSS, Park Avenue, Regency & Riviera

Disassemble

Refer to Figs. and when performing the following procedures.

• Remove master cylinder from vehicle as follows:
• Disconnect and plug hydraulic lines.
• Remove two master cylinder attaching nuts, then the master cylinder.
• Remove reservoir cover and diaphragm. Discard old brake fluid in reservoir.
• Inspect cover and diaphragm.
• Remove fluid level switch, if equipped.
• On models with compact master cylinder, remove proportioner valve assembly, Fig. .
• On all models, depress pri...

Replace

• Raise and support vehicle.
• Mark relationship of wheel to axle flange, then remove wheel and tire assembly.
• Remove brake hose from caliper, Fig. . Plug openings in caliper and brake hose to prevent fluid loss and contamination.
• Lift up on end of cable spring to free end of cable from lever, then disconnect parking brake cable from lever.
• Remove bolt and washer attaching cable support bracket to caliper body assembly.
• Remove sleeve bolt and caliper body assembly.
• Reverse procedure to install, noting the following:
• Torque sleeve bolt to 20 ft. lbs.
• Torque cable support bracket to 32...

Replace

• Remove approximately ^2/3 of brake fluid from master cylinder.
• Raise and support front of vehicle, then remove wheel and tire assembly.
• Using suitable C-clamp, push piston back into caliper bore, Fig. .
• If caliper assembly is being removed for service, remove inlet fitting attaching bolt, copper washer, and inlet fitting from caliper housing. Plug opening in inlet fitting to prevent fluid loss and contamination. Do not crimp brake hose, as this may damage internal structure of hose. If only shoe and lining assemblies are to be replaced, do not disconnect brake line fitting fr...