Truck Electrical Circuit Fundamentals Part B 190404aB

Question 1

1. What component prevents all the warning lights from illuminating when one warning
   light is illuminated?
   a) fusible link
   b) buzzer
   c) relays
   d) isolating diodes

Answer 1

d) isolating diodes

Question 2

2. Explain how the alternator R terminal indicates that the alternator is not charging.

Answer 2

2. By using the alternator (R) or relay terminal and a relay. The only time a voltage is
   available from the relay terminal is when the alternator is generating an output. When
   you turn the ignition switch on, with the engine not running, the warning lamp
   illuminates; this occurs by means of current from the ignition switch passing through
   the normally closed contacts of the relay. When the alternator starts to charge,
   voltage from the alternator relay terminal energizes the relay windings. This moves
   the armature within the relay from terminal 87a to terminal 87, opening the circuit.
   This causes the light to go out.

Question 3

3. List the three (3) types of analog gauges.

Answer 3

3. a) balancing coil gauge
   b) stepper motor gauge
   c) air core gauge

Question 4

4. How does a digital gauge receive its signal?
   a) from fiber optic cable
   b) by an analog signal from the sending unit
   c) over the truck’s data link
   d) by a capillary tube

Answer 4

4. c) over the truck’s data link

Question 5

5. A Hall effect sensor sends an amperage signal to the ammeter by:
   a) measuring the current along the shunt.
   b) using an integrated circuit amplifier.
   c) reversing the current flow.
   d) grounding the signal from the alternator.

Answer 5

5. b) using an integrated circuit amplifier.

Question 6

6. Calculate the PPM for a truck equipped with a rear axle ratio of 4.56, tire revs/mile of
   518 and a chopper wheel with 16 teeth.
   a) 25983
   b) 34063
   c) 37793
   d) 46081

Answer 6

6. c) 37793

Question 7

7. What term describes the speed of data transfer over a network?
   a) bits per second
   b) baud rate
   c) data transfer rate
   d) protocol

Answer 7

7. b) baud rate

Question 8

8. What term describes the communication network that connects to all of the
   multiplexed components of a vehicle system?
   a) Controller Area Network
   b) protocol
   c) topology
   d) data bus

Answer 8

8. d) data bus

Question 9

9. What term describes the logic structure of the control modules in which no single
   module has priority over another?
   a) Controller Area Network
   b) protocol
   c) topology
   d) data bus

Answer 9

9. c) topology

Question 10

10. What te1m describes a common language communicated between control modules?
    a) Controller Area Network
    b) protocol
    c) topology
    d) data bus

Answer 10

10. b) protocol

Question 11

11. Multiplexing reduces the number of conductors used on heavy equipment by:
    a) eliminating redundant outputs.
    b) reducing the number of control modules.
    c) using larger conductor gauges.
    d) allowing control modules to share data for inputs.

Answer 11

11. d) allowing control modules to share data for inputs.

Question 12

12. What determines if an information bit is dominate (0) or recessive (1) on a J1939 data link?
    a. between pins A and B
    b. between pins A and G
    c. between pins A and F
    d. between pins F and G

Answer 12

b. between pins A and G

Question 13

13. Which of the following identifies where a specific failure has occurred?
    a. suspect parameter number (spn)
    b. parameter group number (PGN)
    c. failure mode identifier (FMI)
    d. subsystem identifier (SID)

Answer 13

a. suspect parameter number (SPN)

Question 14

14. When testing the J1939/CAN data link resistance, between which two pins do you take the resistance check?
    a. pins A and B
    b. pins C and D
    c. pins E and F
    d. pins G and H

Answer 14

b. pins C and D

Question 15

Which of the following modules control other modules?
a. switch expansion module (SEM)
b. expansion module (EXM)
c. chassis control module (CHM)
d. bulkhead control module (BHM)

Answer 15

d. bulkhead control module (BHM)

Question 16

16. Explain how the alternator R terminal indicates that the alternator is not charging.

Answer 16

Using alternator terminal R and a relay. The only time a voltage is available from the relay terminal is when the alternator is generating an output. With ignition on engine off, the normally closed relay terminal turns the warning light on. When the alternator is charging, it closes the relay and the light goes out.

Question 17

17. How does a digital gauge receive it’s signal?
    a. from fiber optic cable.
    b. by an analog signal from the sending unit.
    c. over the truck’s data link.
    d. by a capillary tube.

Answer 17

c. over the truck’s data link

Question 18

18. Calculate the PPM for a truck equipped with a rear axle ratio of t.56, tire revs/mile of 518 and a chopper wheel with 16 teeth.
    a. 25983
    b. 34063
    c. 37793
    d. 46081

Answer 18

c. 37793

Question 19

19. What term describes the communication network that connects to all of the multiplexed components of a vehicle system?
    a. Controller Area Network
    b. protocol
    c. topology
    d. data bus

Answer 19

d. data bus

Question 20

20. What is the baud rate of J1939 -11/CAN2.0 data link?
    a) 9.6 kb/s
    b) 100 kb/s
    c) 250 kb/s
    d) 1.0 Mb/s

Answer 20

c. 250 kb/s

Question 21

21. Message corruption is reduced on a J1587/Jl 708 data link by using a/n:
    a) unshielded twisted wire pair
    b) shielded twisted wire pair
    c) unshielded twisted wire pair and terminating resistors
    d) shielded twisted wire pair and terminating resistors

Answer 21

a. unshielded twisted wire pair`

Question 22

22. Which of the following best describes the function of the parameter identifier (PID)?
    a) indicates the source address of the transmitting node
    b) indicates what parameter the message contains
    c) terminates the message
    d) defines the type of failure

Answer 22

b. indicates the parameter the message contains

Question 23

23. Which of the following best describes the failure mode identifier (FMI)?
    a) indicates the source address of the transmitting node
    b) indicates what parameter the message contains
    c) terminates the message
    d) defines the type of failure

Answer 23

d. defines the type of failure

Question 24

24. What protocol does the 11939 data link use?
    a) 11708
    b) J1939-11
    c) CAN
    d) SAE

Answer 24

c. CAN

Question 25

25. Which of the following best describes the unique number assigned to every message?
    a) suspect parameter number (SPN)
    b) parameter group number (PGN)
    c) failure mode identifier (FMI)
    d) subsystem identifier (SID)

Answer 25

b) parameter group number (PGN)

Question 26

26. Terminating resistors are used to terminate the signal on a J1939 data link in order to:
    a) prevent standing waves from occurring
    b) drop the data link voltage to spec
    c) reduce the chance of large voltage spikes occurring
    d) increase data link resistance to 240 ohms

Answer 26

a. prevent standing waves from occurring

Question 27

27. What is the expected result when testing the resistance of the J1939?
    a) 60 0
    b) 120 O
    c) 240 .0
    d) 1-4MO

Answer 27

A. 60 ohms