Air ABS Systems

All of the following could cause a failure in an air ABS system except:

shorted solenoid coils

leaking hydraulic lines

blocked exhaust solenoid ports

no power to the ECU

Correct! Wrong!

The warning light on a truck with anti-lock brakes comes on when the truck key is turned on, the truck started and stays on when the truck is moving. Which of the following could be the cause?

misadjusted wheel sensor

faulty quick release valve

blown failsafe mode fuse

low governor setting

Correct! Wrong!

an LED light flashes a code directing the driver when to apply the brakes

the ABS system shuts down and a warning light comes on

the failsafe device shifts to a secondary ABS system

the entire braking system shuts down

Correct! Wrong!

What happens if an ABS system component ceases to function?

Some ABS systems may use two micro processors. In these systems, both must agree on diagnosis and commands or the system will go into "failsafe" mode.

True

False

Correct! Wrong!

Technician A says some ABS systems use a series of light emitting diodes (LED''s) on a panel to indicate faults. Technician B says that the signal from the wheel sensors produce an A/C signal that is proportional to wheel speed. Who is correct?

A

B

Both A and B

Neither A nor B

Correct! Wrong!

Technician A says that wheel sensors are electromagnetic pulse generators used to obtain wheel speed information. Technician B says that the signal from the wheel sensors produce an A/C signal that is proportional to wheel speed. Who is correct?

A

B

Both A and B

Neither A nor B

Correct! Wrong!

If an ABS system has one modulator valve on a single avle, and one wheel is on ice and starts to look up, while the other is on dry pavement with good traction, the ABS system will:

only control the wheel on the ice

only control the wheel on the dry pavement

control both wheels simultaneously

have no effect

Correct! Wrong!

ABS systems will help to correct for misadjusted and unbalanced brakes.

True

False

Correct! Wrong!

Some ABS systems may incorporate traction control with the addition of the correct ECU and solenoids.

True

False

Correct! Wrong!

ABS trouble codes may be caused by:

high resistance in the wheel sensor circuit

misadjusted wheel sensors

disconnected components that transmit signals to the ECU

All of the above

Correct! Wrong!

When applied on steering axles, functioning ABS systems provide for better steering control, preventing lock-up on slippery surfaces.

True

False

Correct! Wrong!

Technician A says that some ABS ECU uses a series of light emitting diodes (LED''s) in a diagnostic window to indicate fault codes in the ECU. Technician B says that the number of LEDs in the diagnostic window vary depending on the system. Who is right?

A only

B only

Both A and B

Neither A nor B

Correct! Wrong!

Technician A says that wheel and axle sensors are electromagnetic devices used to obtain vehicle speed information. Technician B says that when an ABS system is disabled, the vehicle goes into its standard braking mode. Who is right?

A only

B only

Both A and B

Neither A nor B

Correct! Wrong!

On anti-skid brake systems, "Fail Safe" refers to a vehicle''s ability:

to automatically apply spring brakes in the case of computer failure

to make normal stops in the case of anti-skid component failure with only the anti-skid feature lost

to make normal stops in the case of anti-skid component failure using a back-up computer

automatically apply 50% trailer braking

Correct! Wrong!

Diagnosis of some anti-skid brake systems may be made with an on-board diagnostic system.

True

False

Correct! Wrong!

Anti-skid brake systems aid with foundation brake balance and timing.

True

False

Correct! Wrong!

The ECU and/or module used to control an ABS system may be mounted directly to the relay valve on some systems.

True

False

Correct! Wrong!

What happens when a failure is detected in an ABS system?

the ECU will no longer monitor inputs from that portion of the system and lights the dash indicator

full function ABS will still be available

the ECU will completely shut down

the ECU will delay implementing a default until approximately 5 minutes have elapsed

Correct! Wrong!

Once a failure is sensed by the ECU, the information is stored in memory until the

vehicle is shut down

repair is completed

system is reset

next automatic self check takes place

Correct! Wrong!

Technician A says that a broken wheel speed sensor wire can be fixed with a simple butt connector splice or equivalent. Technician B says that the proper repair is to replace the entire wheel speed sensor to fix the vehicle. Who is right?

A only

B only

Both A and B

Neither A nor B

Correct! Wrong!

An ABS system on a truck is being inspected. Technician A says that in many systems, there is one module per axle, which means that each axle brakes as one unit. Technician B says that in many truck ABS systems, there are two modules per axle, are designed to handle any differential in road friction situations when they occur. Who is right?

B only

Both A and B

Neither A nor B

Correct! Wrong!

The modulation process of braking and the resulting actions of anti-lock brake systems involves three main sections. There are speed sensing, decision making, and brake ___________?

applying

modulating

balancing

releasing

Correct! Wrong!

The National Transportation Safety Board (NTSB) requires:

that all trucks with a gross vehicle rating (GVWR) over 10,000 pounds have dual-action braking

that all new trucks, trailers, and heavy tractors built after 1996 be equipped with an antilock braking system

that all trucks over 20,000 pounds GVWR have type 35 rotochambers

that all trucks, buses, heavy tractors, and trailers be equipped with forged steel brake chamber pushrods that have at least 50,000 pound tensile strength

Correct! Wrong!

A wheel sensor from an ABS system is being inspected. Technician A says that as the toothed wheel rotates, the sensor generates a simple DC signal. Technician B says that the waveform signal generated is AC and the signal is proportional to wheel speed. Who is right?

A only

B only

Both A and B

Neither A nor B

Correct! Wrong!

What happens if the ABS system ceases to function?

an LED light flashes a code directing the driver when to apply the brakes

the system shuts down to failsafe mode and a warning life comes on

a failsafe device shifts to a secondary ABS system

the entire braking system shuts down

Correct! Wrong!

Air ABS Systems

All of the following could cause a failure in an air ABS system except:

The warning light on a truck with anti-lock brakes comes on when the truck key is turned on, the truck started and stays on when the truck is moving. Which of the following could be the cause?

Some ABS systems may use two micro processors. In these systems, both must agree on diagnosis and commands or the system will go into "failsafe" mode.

Technician A says some ABS systems use a series of light emitting diodes (LED''s) on a panel to indicate faults. Technician B says that the signal from the wheel sensors produce an A/C signal that is proportional to wheel speed. Who is correct?

Technician A says that wheel sensors are electromagnetic pulse generators used to obtain wheel speed information. Technician B says that the signal from the wheel sensors produce an A/C signal that is proportional to wheel speed. Who is correct?

If an ABS system has one modulator valve on a single avle, and one wheel is on ice and starts to look up, while the other is on dry pavement with good traction, the ABS system will:

ABS systems will help to correct for misadjusted and unbalanced brakes.

Some ABS systems may incorporate traction control with the addition of the correct ECU and solenoids.

ABS trouble codes may be caused by:

When applied on steering axles, functioning ABS systems provide for better steering control, preventing lock-up on slippery surfaces.

Technician A says that some ABS ECU uses a series of light emitting diodes (LED''s) in a diagnostic window to indicate fault codes in the ECU. Technician B says that the number of LEDs in the diagnostic window vary depending on the system. Who is right?

Technician A says that wheel and axle sensors are electromagnetic devices used to obtain vehicle speed information. Technician B says that when an ABS system is disabled, the vehicle goes into its standard braking mode. Who is right?

On anti-skid brake systems, "Fail Safe" refers to a vehicle''s ability:

Diagnosis of some anti-skid brake systems may be made with an on-board diagnostic system.

Anti-skid brake systems aid with foundation brake balance and timing.

The ECU and/or module used to control an ABS system may be mounted directly to the relay valve on some systems.

What happens when a failure is detected in an ABS system?

Once a failure is sensed by the ECU, the information is stored in memory until the

Technician A says that a broken wheel speed sensor wire can be fixed with a simple butt connector splice or equivalent. Technician B says that the proper repair is to replace the entire wheel speed sensor to fix the vehicle. Who is right?

The modulation process of braking and the resulting actions of anti-lock brake systems involves three main sections. There are speed sensing, decision making, and brake ___________?

The National Transportation Safety Board (NTSB) requires:

A wheel sensor from an ABS system is being inspected. Technician A says that as the toothed wheel rotates, the sensor generates a simple DC signal. Technician B says that the waveform signal generated is AC and the signal is proportional to wheel speed. Who is right?

What happens if the ABS system ceases to function?

Success!

Heavy-Duty Mechanic - Trucks & Equipment