Brake Systems & Suspension Flashcards

An ABS wheel speed sensor has too large an air gap. What is the most likely result?

Answer: A weak or erratic signal, especially at low speed, setting an ABS code

A larger air gap weakens the magnetic signal, which is weakest at low speeds, so the module may see dropouts and set a code.

What kind of signal does a passive (magnetic reluctance) wheel speed sensor produce?

Answer: AC voltage whose frequency and amplitude increase with wheel speed

A passive sensor generates an AC sine wave whose frequency and amplitude rise as the tone ring spins faster.

During a hard stop, a driver feels rapid brake pedal pulsation and hears a buzzing noise while the ABS warning light stays off. What does this indicate?

Answer: Normal ABS operation

Pedal pulsation and pump noise are normal when the ABS modulator cycles pressure during a stop.

On many star-wheel self-adjusting duo-servo drum brakes, when does the adjuster normally operate?

Answer: When the brakes are applied while the vehicle moves in reverse

Most duo-servo self-adjusters work when the brakes are applied in reverse, as the secondary shoe moves the adjuster lever.

In a duo-servo drum brake, which shoe usually has the longer lining because it does most of the braking work?

Answer: The secondary (rear-facing) shoe

Servo action makes the secondary shoe apply harder, so it carries the longer lining.

Replacing pads on a rear disc caliper with an integral parking brake mechanism usually requires what step?

Answer: Rotate (screw) the caliper piston back in with a special tool

Integral parking brake pistons are threaded on an internal screw, so they must be turned while being pushed back in.

A Hydro-Boost power brake system gets its assist from which source?

Answer: Power steering pump hydraulic pressure

Hydro-Boost uses pressurized fluid from the power steering pump and is common on diesels and heavy-duty trucks.