Brakes Ch. 16-18
Tech B
A customer wanted the ABS checked because of tire chirp noise during hard braking. Technician A says that the speed sensors may be defective. Technician B says that tire chirp is normal during an ABS stop on dry pavement. Which technician is correct?
A. Hard brake pedal
A defective vacuum brake booster will cause a: A. Hard brake pedal B. Soft (spongy) brake pedal C. Slight hiss noise when the brake pedal is depressed D. Low brake pedal E. Any of the above depending on the fault.
Technician B
A digital wheel sensor is being tested. Technician A says the signal voltage will normally switch from about 0 volts to almost 12 volts when the wheel is rotated by hand. Technician B says the signal voltage will normally switch from .8 volts to almost 2 volts when the wheel is rotated by hand. Which technician is correct?
D. Square wave
A digital wheel speed sensor produces a(an) ________ type of signal. A. Sine wave B. AC analog C. Varying voltage D. Square wave
D. An accumulator
A hydraulically operated booster unit stores fluid under pressure by means of: A. An actuator B. A boost piston C. A hydraulic check valve D. An accumulator
B. The amber ABS warning light should illuminate
A quick diagnostic test of wheel speed sensors (WSS) on some Bosch ABS systems is to hoist the vehicle and spin each tire individually. If the WSS is working properly: A) The red brake warning light should illuminate B) The amber ABS warning light should illuminate C) Both A and B are correct D) Neither A nor B is correct
B. 2
A rear-wheel antilock braking system usually uses how many solenoids (valves)? A. 1 B. 2 C. 3 D. 4
E. Both A & C
A technician is trying to identify which type of antilock system is installed on a vehicle. A wheel speed sensor is attached to the transmission. Which type of system could this be? A. One-channel ABS B. Two-channel ABS C. Three-channel ABS D. Four-channel ABS E. Both A & C
B. False
A vacuum is described as any pressure that is higher than atmospheric pressure. A. True B. False
D. A concern not related to the ABS system
A vehicle quipped with ABS exhibits a brake pull when the brakes are applied firmly. The amber ABS indicator on the dash proves out when started but goes out after the ignition on cycle. The most likely cause of the brake pull is: A. A stuck ABS isolation valve B. A faulty wheel speed sensor C. A stuck ABS pressure release valve D. A concern not related to the ABS system
D. All of these are possible causes
A wheel speed sensor is producing lower than expected voltage as the wheel rotates. Which of these is NOT a possible cause? A. Incorrect air gap between the sensor and toothed ring B. Damaged or corroded electrical connector C. Debris on the sensor D. All of these are possible causes
B. Scan tool
Air trapped within a replacement ABS hydraulic unit may require the use of a ________ to bleed out the air. A. dead blow hammer B. scan tool C. vacuum pump D. brake pedal depressor
E. All the above
Brake vacuum booster pushrod adjustment: A. should be checked whenever the booster is replaced. B. should be checked whenever the master cylinder is replaced. C. if adjusted incorrectly will cause the brakes to overheat. D. Only A & B Correct! E. All the above
B. 5 and 20 percent
Modern antilock brake systems typically hold tire slip on dry pavement to between: A. 0 and 10 percent B. 5 and 20 percent C. 10 and 30 percent D. 20 and 40 percent
D. 800 to 1,300 ohms
Most passive wheel speed sensors should measure how much resistance? A. 0.1 to 1 ohm B. 1 to 3 ohms C. 100 to 300 ohms D. 800 to 1,300 ohms
1 for 16 2 for 17
Study Images on quizzes!!!!!!!!!!!!!!
Tech B
Technician A says an antilock brake system will always produce the shortest possible stops. Technician B says when braking on loose gravel or dirt, a system that can lock the wheels can produce shorter stops than an antilock system. Which technician is correct?
Tech A
Technician A says even though the driver is turning the steering wheel, the vehicle will continue in a straight line if the front wheels are locked. Technician B says the ABS system operates at a higher pressure than the driver does with his/her foot. Who is right?
Both tech A and B
Technician A says interference from a CB radio antenna may disrupt ABS system performance. Technician B says a faulty alternator could cause the ABS warning lamp to light. Which technician is correct?
Tech A
Technician A says power brakes were developed because of increased vehicle weight and increased speed capabilities. Technician B says disc brakes systems all operate with power assist. Which technician is correct?
Both tech A and B
Technician A says some ABS systems use hydraulic pressure generated by the power steering pump to assist in antilock braking. Technician B says some ABS systems use electric motors to control the hydraulic valves instead of solenoids? Which technician is correct?
Both tech A and B
Technician A says that ABS may not result in shorter stopping distances compared to brakes without ABS. Technician B says that a pulsating brake pedal during severe braking is a characteristic of most ABS-equipped vehicles. Which technician is correct?
Tech B
Technician A says that ABS-equipped vehicles can stop quickly and without skidding on all road surfaces even if covered with ice. Technician B says that steering is possible during an ABS stop. Which technician is correct?
Both tech A and B
Technician A says that a noise or vibration may be sensed by the driver when the ABS performs a self test. Technician B says that the ABS fuse may have to be removed to erase some ABS diagnostic codes if a scan tool is not used. Which technician is correct?
Both A and B
Technician A says that a scan tool may be required to retrieve data and diagnostic trouble codes from some antilock braking systems. Technician B says that a jumper wire can be used to retrieve diagnostic codes on some antilock braking systems. Which technician is correct?
Tech A
Technician A says that incorrect tire size could cause a wheel speed sensor code. Technician B says that changing the tire size will have no effect on the ABS system in any way. Which technician is correct?
Tech B
Technician A says that most ABS units are the integral type. Technician B says that the ABS is disabled (does not function) below about 5 mph (8 km/h). Which technician is correct?
Both tech A and B
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?
Tech A
Technician A says that using the space saving small spare tire may trigger an ABS amber warning lamp. Technician B says the use of the small spare tire may trigger the red brake warning lamp. Which technician is correct?
Both tech A and B
Technician A says that, with some antilock braking systems, the diagnostic trouble code may be lost if the ignition is turned off before retrieving the code. Technician B says that some antilock braking systems require that a terminal be grounded to cause the amber ABS warning lamp to flash diagnostic trouble codes. Which technician is correct?
Neither A nor B
Technician A states a magnetic-inductive WSS is an active speed sensor. Technician B states a magnetic-inductive WSS produces DC voltage. Which technician is correct?
A. Frequency
The ABS computer uses what signal characteristic from a wheel speed sensor to determine wheel speed? A. Frequency B. Voltage C. Resistance D. Amperage
A. Frequency
The ABS control module uses the ________ signal from a wheel speed sensor. A. Frequency B. Voltage C. Resistance D. Amperage
E. 3,300 psi (23,000 kPa)
The peak accumulator pressure developed by an ABS hydraulic pump may be as high as: A. 600 psi (4137 kPa) B. 1,200 psi (8274 kPa) C. 1,800 psi (12,573 kPa) D. 2,700 psi (18,616 kPa) E. 3,300 psi (23,000 kPa)
B. 15 in. Hg vacuum
The proper operation of a vacuum brake booster requires that the engine be capable of supplying at least: A. 13 in. Hg vacuum B. 15 in. Hg vacuum C. 17 in. Hg vacuum D. 19 in. Hg vacuum
D. trap gasoline vapors to keep them from entering the booster
The purpose of the charcoal filter in the vacuum hose between the engine and the vacuum brake booster is to: A. filter the air entering the engine from the power booster. B. dampen the vacuum fluctuations from the engine. C. act as a one-way check valve to help keep a vacuum reserve in the booster D. trap gasoline vapors to keep them from entering the booster
D. ABS system fault
The red brake warning lamp is dimly lit on a RWD S10 pickup with RWAL. Which is the most likely cause? A. Parking brake circuit malfunction B. Hydraulic system failure C. Low resistance in the warning light circuit D. ABS system fault E. None of the above are correct
Tech A
The red brake warning lamp is on and the amber ABS lamp is off. Technician A says that a fault is possible in the base brake system. Technician B says that the red brake warning lamp can be turned on by a faulty wheel speed sensor. Which technician is correct?
C. Hold, release, increase
The three phases of ABS operation are pressure: A. Hold, clamp, revise B. Release, hold, reverse C. Hold, release, increase D. Release, hold, insulate
A. Reaction disc
To provide the driver with a sense of "feel" during braking, vacuum boosters use a: A. Reaction disc B. Pressure restriction in the vacuum line C. Diaphragm spacer D. Vacuum diverter
Tech A
Two technicians are discussing ABS wheel speed sensors. Technician A says that some ABS use a sensor located in the rear-axle pinion gear area. Technician B says that all ABS use a wheel speed sensor at each wheel. Which technician is correct?
Tech A
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?
Both tech A and B
Two technicians are discussing vacuum suspended 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, engine vacuum is present on the front side of the diaphragm. Which technician is correct?
A. Brake pedal switch
What causes the ABS control module to switch from a "stand-by" mode to an active mode? A. Brake pedal switch B. Sudden application of the brakes C. Wheel deceleration, as sensed by the wheel speed sensor(s) D. Vehicle speed sensor
C. They open and close hydraulic passageways
What is the function of the ABS solenoids? A. They create pressure on the brake pedal B. To initiate master cylinder pressure C. They open and close hydraulic passageways D. They directly apply the brake pads
D. Discharge the accumulator
What precaution should be taken before servicing an ABS that uses a high pressure accumulator? A. Drain the fluid before service B. Disconnect the negative cable from the battery C. Remove the air bag fuse D. Discharge the accumulator
B. 12 volts DC
What reference voltage (supply voltage) is usually used with digital (active) wheel speed sensors? A. 5 volts DC B. 12 volts DC C. 12 volts AC D. None of these, the digital sensor generates its own voltage signal
B. Replace the check valve
When blowing through the vacuum supply hose, if air passes through the check valve into the booster: A. Replace the vacuum pump B. Replace the check valve C. Replace the booster D. The check valve is functioning properly
C) Both A and B are correct
When observing a passive WSS output with an oscilloscope, sensors should produce: A) An AC sine wave that increases in frequency as wheel speed increases B) An AC sine wave that increases in amplitude as wheel speed increases C) Both A and B are correct D) Neither A nor B is correct
D. sink slightly toward the floor, then push back against your foot.
When performing a hydro-boost brake booster function test the brake pedal should be depressed several times to discharge the accumulator. When the engine is started, with your foot on the brake pedal, the pedal should: A. push back against your foot. B. push back then sink slightly toward the floor. C. sink slightly toward the floor. D. sink slightly toward the floor, then push back against your foot.
B. Hydraulic modulator unit
Which of the following components is common to all vehicles equipped with ABS? A. Individual wheel speed senors B. Hydraulic modulator unit C. Brake pedal travel sensor D. Yaw sensor.
C. Allows drivers to drive more closely to the vehicle in front
Which of the following is NOT a function of an antilock brake system (ABS)? A. Maintain directional stability on slippery surfaces B. Helps maintain vehicle control while braking C. Allows drivers to drive more closely to the vehicle in front D. Regenerates fluid condition
