Brake Pulsation (With RPO HP5)

DEFINITION:

• Fluctuation or pulsation is felt through the brake pedal, steering wheel, seat, floor, and/or in the vehicle ONLY when braking.
• Notchy or uneven brake pedal feel during brake apply.
• Kickback is felt through the brake pedal during brake apply and release.

1. Inspect the disc brake system for the following conditions.
   • Excessive thickness variation of rotor friction surfaces
   • Excessive assembled lateral runout (LRO) of rotor friction surfaces
   • Hard spots, heat checks, bluing discoloration of rotor friction surfaces; possibly due to brake drag
   • Excessive corrosion of rotor friction surfaces; including red, gray or black oxidation
   • Loose, damaged or missing caliper or lining hardware
   • Bent or damaged caliper or mounting component
   • Excessive LRO of wheel hub/axle flange; due to damage and/or loose or excessively worn bearings
2. Perform the disc brake system diagnostic procedure. Refer to Disc Brake System Diagnosis .
3. Adjust, repair or replace components as necessary.

1. Inspect the brake hydraulic and assist systems for the following conditions:
   • Lack of lubrication, binding, excessively worn and/or damaged brake pedal pushrod, pin and/or pedal pivot bushings.
   • Bent or damaged pedal pushrod, pedal, or pedal bracket.
   • Restricted brake master cylinder reservoir-to-brake pressure modulator valve (BPMV) feed and/or return hoses.
2. Perform the entire brake and hydraulic assist system diagnostic procedure. Refer to Brake Hydraulic and Assist System Diagnosis (Two-mode Hybrid) .
3. Adjust, repair or replace components as necessary.

1. Replace the brake master cylinder for sticking or improperly functioning pistons. Refer to Master Cylinder Replacement (Without RPO HP5)  or Master Cylinder Replacement (With RPO HP5) .
2. Pressure bleed the hydraulic brake system. Refer to Hydraulic Brake System Bleeding (Manual)  or Hydraulic Brake System Bleeding (Pressure) .
3. Perform the entire Antilock Brake System Automated Bleed Procedure .

1. Replace the brake pressure modulator valve (BPMV) for an improperly functioning boost circuit. Refer to Brake Pressure Modulator Valve Replacement .
2. Pressure bleed the hydraulic brake system. Refer to Hydraulic Brake System Bleeding (Manual)  or Hydraulic Brake System Bleeding (Pressure) .
3. Perform the entire Antilock Brake System Automated Bleed Procedure .

1. Install or connect components that were removed or disconnected during diagnosis.
2. Road test the vehicle in order to confirm proper operation. Refer to Brake System Vehicle Road Test .