Automotive and Mechanics Brake Systems 3

Question 1

Which ABS component directly modulates hydraulic brake pressure to individual wheels during an ABS-activated stop?

Accepted Answer

Hydraulic control unit (HCU) / modulator assembly

Answer

The hydraulic control unit contains solenoid valves that cycle open and closed many times per second to modulate fluid pressure at each wheel during ABS activation.

Question 2

Brake rotor lateral runout (side-to-side wobble) is measured using which instrument?

Accepted Answer

Dial indicator

Answer

A dial indicator is mounted to a fixed point while the rotor is slowly rotated; the needle's total movement indicates the amount of lateral runout.

Question 3

A brake caliper that seizes in the partially applied position will most likely cause which symptom?

Accepted Answer

Accelerated wear on one brake pad and excessive heat at that wheel corner

Answer

A seized caliper keeps its pad in continuous contact with the rotor, resulting in rapid uneven pad wear and dangerous heat buildup at that wheel.

Question 4

Electronic Stability Control (ESC) improves vehicle stability during cornering primarily by:

Accepted Answer

Selectively applying brakes to individual wheels to correct understeer or oversteer

Answer

ESC uses yaw rate and steering angle sensors to detect loss of directional control and selectively applies one or more individual wheel brakes to steer the vehicle back on course.

Question 5

A rhythmic pulsation or vibration felt through the brake pedal during braking is most often caused by:

Accepted Answer

Excessive rotor lateral runout or disc thickness variation (DTV)

Answer

Rotor lateral runout or disc thickness variation causes the caliper pistons to pump in and out as the rotor rotates unevenly, creating a pedal pulsation felt by the driver.

Automotive and Mechanics Practice Test

Automotive and Mechanics Practice Test

Automotive and Mechanics Brake Systems 3