Automobile & Light Truck Certification Test A5 BrakesDisc Brake Diagnosis and RepairHard
A customer reports that their vehicle pulls sharply to the left when the brakes are applied. The technician verifies the complaint and finds no obvious fluid leaks or unusual noises. Which of the following is the most likely cause?
- AA collapsed brake hose on the left front wheel.
- BA seized caliper piston on the right front wheel.
- CAn air bubble in the right rear brake line.
- DExcessive runout on the left front rotor.
Show answer & explanationAnswer & explanation
Correct answer: B. A seized caliper piston on the right front wheel.
If the vehicle pulls sharply to the left during braking, it indicates that the left front brake is applying significantly more force than the right front brake. A seized caliper piston on the right front wheel would prevent that brake from applying full force, leading to the vehicle pulling towards the side with effective braking (the left side).
Why the other options are wrong
- A. A collapsed brake hose on the left front wheel would restrict fluid flow, causing reduced braking on the left side, which would make the vehicle pull to the *right* (towards the working right brake).
- C. An air bubble in the right rear brake line would reduce braking force on the right rear, causing a slight pull to the left rear, but not a 'sharp pull' from the front brakes.
- D. Excessive runout on the left front rotor would typically cause brake pulsation, not a sharp pull to one side, unless it was so severe as to prevent proper pad contact.
Brake Pull Diagnosis
A vehicle pulling to one side during braking indicates unequal braking force between the left and right wheels, often due to a malfunctioning caliper or restricted brake hose on one side.
- Pull towards the side with stronger braking.
- Pull away from the side with weaker/no braking.
- Common causes: seized calipers, collapsed hoses.
Memory trick: Pull to the left? Right brake's put to the test!