Exam 105: Power Brake Unit Operation, Diagnosis, and Service

What component is the technician holding in this photograph?

Technician A says that to check the operation of a vacuum brake booster, the brake pedal should be depressed until the assist is depleted and then start the engine. Technician B says that the brake pedal should drop when the engine starts, if the booster is okay. Which technician is correct?

A common source of vacuum for boosters used on diesel engines is ________.

Two technicians are discussing vacuum brake boosters. Technician A says that when the engine is running and the driver's foot is off the brake pedal, a vacuum is present on both sides of the booster diaphragm. Technician B says that when the brakes are in the applied position, vacuum is present on the front side of the diaphragm. Which technician is correct?

Brake pedal feedback to the driver is provided by the ________.

The booster operation test determines if the booster is ________.

The first step in diagnosing a Hydro-Boost problem is ________.

The brake assist system (BAS) is activated ________.

Technician A says when the brakes are applied in a vacuum booster, the vacuum control valve is sealed.Technician B says the vacuum control valve is opened. Which technician is correct?

A hydraulically operated booster unit stores fluid under pressure by means of ________.

The Hydro-Boost brake booster uses what type of fluid to multiply brake pedal force?

The pushrod length should be checked whenever a new master cylinder is installed.

Two technicians are discussing vacuum brake boosters. Technician A says that a low, soft brake pedal is an indication of a defective booster. Technician B says that there should be at least two power-assisted brake applications after the engine stops running. Which technician is correct?

An accumulator such as that used on hydraulic brake boosters ________.

Technician A says the vacuum supply test involves inspecting the vacuum supply hose for kinks. Technician B says the test involves checking the level of vacuum supplied by the engine or vacuum pump. Which technician is correct?

If the engine stops running, the Hydro-Boost will not be able to provide any power assist for the brakes.

A brake pedal feels spongy when depressed. Technician A says that a defective hydraulic brake booster could be the cause. Technician B says that a defective vacuum brake booster could be the cause. Which technician is correct?

The purpose of the charcoal filter in the vacuum hose between the engine and the vacuum brake booster is to ________.

A Hydro-Boost unit uses the power steering pump as a source of power.

To provide the driver with a sense of "feel" during braking, vacuum boosters use a ________.