Air antilock brake system fundamentals

Question 1

1. What are the two (2) primary functions of an ABS system?
   a)
   b)

Answer 1

a) to help the operator maintain control throughout the braking application under
less than ideal conditions
b) to improve the chances of reducing overall stopping distances

Question 2

2. The tone ring is typically part of or attached to the:
   a) spindle.
   b) drive shaft.
   c) brake drum.
   d) wheel hub.

Answer 2

d) wheel hub.

Question 3

3. The modulator valves send and receive signals to and from the ECU.
   a) true
   b) false

Answer 3

b) false; the modulator does not send signals to the ECU

Question 4

4. The wheel speed sensor sends a pulsed signal to the ECU.
   a) true
   b) false

Answer 4

a) true

Question 5

5. Which of the following is a four-channel system?
   a) 2S/2M
   b) 4S/3M
   c) 6S/4M
   d) 6S/6M

Answer 5

c) 6S/4M

Question 6

6. A tandem axle truck, tractor or bus has air ride suspension and a 4S/4M system.
   Which axle(s) would typically have wheel speed sensors?
   a) front drive axle
   b) rear drive axle
   c) neither drive axles
   d) both drive axles

Answer 6

b) rear drive axle

Question 7

7. The order in which the ECU instructs the modulator valve to control air pressure is:
   a) hold, reapply and exhaust.
   b) reapply, exhaust and hold.
   c) exhaust, hold and reapply.
   d) exhaust, reapply and hold.

Answer 7

c) exhaust, hold and reapply.

Question 8

8. Where are electronic control modules mounted on truck/tractors, buses and trailers?

Answer 8

inside the truck cab or bus baggage compartment, mounted to the frame or cross
member or attached directly to the trailer air reservoir.

Question 9

9. On initial start-up, the ABS warning lamp lights up and stays on to indicate to the
   operator that:
   a) the system is active (modulating).
   b) the system could be functioning properly, but must be driven above 5 to 10
   km/h to confirm.
   c) there is an existing fault code.
   d) either b or c.

Answer 9

d) either b or c.

Question 10

10. Engine, exhaust and driveline retarders have sufficient braking capabilities to
    produce a wheel lockup condition and the ABS system, to be effective, must be able
    to turn them off.
    a) true
    b) false

Answer 10

. a) true

Question 11

11. During a normal braking situation, the antilock ECU:
    a) only monitors wheel speeds.
    b) cycles the modulator valves.
    c) lights the indicator lamp.
    d) powers down to a sleep mode

Answer 11

a) only monitors wheel speeds.

Question 12

12. As of March 1, 1998, the trailer antilock ECU receives its power from:
    a) an onboard power source.
    b) the auxiliary pin of the trailer cord.
    c) the tail light pin of the trailer cord.
    d) the largest pin of the trailer cord.

Answer 12

b) the auxiliary pin of the trailer cord.

Question 13

13. During a braking situation, the ATC valve:
    a) receives a signal from the ECU.
    b) sends supply air out the delivery port to apply the relay valve.
    c) modulates application pressure.
    d) allows brake application pressure to pass out the delivery port.

Answer 13

d) allows brake application pressure to pass out the delivery port.

Question 14

14. The ATC indicator/warning lamp is used to:
    a) indicate to the operator that the system is active.
    b) indicate that dyno-mode is activated.
    c) indicate that the driver has activated the deep snow/mud switch.
    d) all of the above

Answer 14

d) all of the above

Question 15

15. In order for the ATC system to reduce torque to the drive wheels, the engine must be
    electronically controlled.
    a) true
    b) false

Answer 15

a) true

Question 16

16. Vehicles equipped with ATC:
    a) must not be tested on a chassis dynamometer.
    b) must have the A TC system disabled before testing on a chassis
    dynamometer.
    c) typically produce 20% less torque and horsepower than rated.
    d) typically produce 20% higher torque and horsepower than those without.

Answer 16

b) must have the ATC system disabled before testing on a chassis dynamometer.

Question 17

17. What are the two (2) primary functions of roll stability control?
    a)
    b)

Answer 17

a) help control vehicle stability

b) limit rollover conditions

Question 18

18. What does the ECU monitor in order to respond to excessive speed on a curve?

Answer 18

The ECU measures the lateral or side-to-side movements of the vehicle.

Question 19

19. What two (2) truck systems work with RSC to help reduce reaction time when
    needed?
    a)
    b)

Answer 19

a) antilock brake system

b) electronic engine management

Question 20

20. Explain the difference between roll stability control and electronic stability control.

Answer 20

Roll stability control does not offer direction control of the vehicle.

Question 21

21. What additional component is added to a vehicle equipped with ESC?
    a) roll stability control valve
    b) ATC valve
    c) brake demand pressure switch.
    d) steering angle sensor

Answer 21

d) steering angle sensor

Question 22

22. Which component allows for differential braking of the steer axle to help prevent
spinout or jackknife conditions?
a) ATC valve
b) front axle control valve
c) accelerometer
d) roll stability control valve

Answer 22

b) front axle control valve