During automotive brake inspections and road testing, technicians evaluate specific drivability symptoms to determine underlying mechanical or hydraulic faults. Match each brake system symptom with its most probable root cause.
- Rhythmic brake pedal pulsation and steering wheel shudder when applying brakes at highway speedsExcessive brake rotor lateral runout or disc thickness variation (DTV)
- Excessively hard brake pedal requiring high leg effort with poor stopping assistDefective vacuum booster check valve or ruptured internal booster diaphragm
- Spongy, low brake pedal that temporarily firms up after rapid successive pumpsAir entrained in the hydraulic brake fluid lines
- Vehicle pulls sharply to the left side during moderate to heavy brake applicationSeized right front caliper slide pin or grease-contaminated right front brake pads
Answer
Rhythmic brake pedal pulsation matches excessive rotor lateral runout or DTV; excessively hard pedal matches defective vacuum booster check valve or ruptured diaphragm; spongy pedal that firms up on pumping matches air entrained in hydraulic lines; vehicle pulling to the left matches seized right front caliper slide pin or grease-contaminated right pads.
Each symptom is paired directly with its underlying physical mechanism: rotor thickness variation creates cyclic feedback (pulsation); loss of vacuum multiplication increases pedal resistance (hard pedal); compressed gas bubbles create hydraulic softness (spongy pedal); and asymmetric friction coefficient or mechanical binding at one wheel assembly produces uneven directional torque (pulling).
Step-by-Step Solution
Key Concept
Brake System Fault Isolation and Symptom Diagnosis
Estimated Time:1m 30s