Ch. 49 CAN & Network Communications Certification
Prep 2026 | Complete Question Bank | Latest Update |
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1. hat is the primary benefit of twisting wires in differential BUS
communication?
to simplify installation
to reduce electromagnetic interference
to increase signal strength
to enhance data speed
2. If a vehicle is experiencing communication issues, how would you determine
whether the problem lies within the CAN or Class 2 system?
By checking the voltage levels and wiring configurations specific to
each communication protocol.
By analyzing the vehicle's fuel efficiency.
By replacing the OBD-II connector.
By inspecting the vehicle's model and year.
3. Describe how the characteristics of Controller Area Networks contribute to
vehicle communication systems.
Controller Area Networks are primarily used for data storage in
vehicles.
Controller Area Networks limit communication to only diagnostic
tools.
Controller Area Networks only connect a single device to the vehicle's
system.
, Controller Area Networks provide robust communication that allows
multiple devices to communicate efficiently in vehicles.
4. Describe how twisting wires in a differential BUS communication system
helps in maintaining signal integrity.
Twisting wires enhances the speed of data transmission significantly.
Twisting wires helps to cancel out electromagnetic interference,
thereby maintaining signal integrity.
Twisting wires increases the overall length of the communication line.
Twisting wires simplifies the installation process for technicians.
5. In a scenario where a vehicle's communication system is experiencing
interference, how would implementing differential BUS communication help
resolve the issue?
By minimizing the effects of electrical noise on the signal.
By simplifying the wiring configuration.
By increasing the number of wires used for communication.
By lowering the voltage levels in the system.
6. If a vehicle's Class A network is experiencing communication issues, which
type of application might be affected?
Non-critical vehicle functions such as interior lighting control
Engine management systems requiring real-time data
High-speed data applications for navigation systems
Safety systems like airbag deployment
,7. Describe the significance of the signal ground terminal in the OBD-II data link
connector.
The signal ground terminal is used for power supply to the OBD-II
connector.
The signal ground terminal is responsible for data transmission
between the vehicle and diagnostic tools.
The signal ground terminal connects to the vehicle's battery for
voltage regulation.
The signal ground terminal provides a common reference point for
all communication signals in the vehicle's diagnostic system.
8. Which terminal is designated for Class 2 communication in GM's data link
connector?
Terminal 4
Terminal 1
Terminal 2
Terminal 3
9. If a technician is unable to power their diagnostic tool using the OBD-II
connector, which pin should they check for connectivity issues?
Pin 4
Pin 16
Pin 1
Pin 5
, 10. Describe how a ring link network operates in terms of data transmission
between nodes.
In a ring link network, data travels in one direction around the
circle, passing through each node until it reaches its destination.
In a ring link network, data is transmitted in both directions, creating
redundancy.
In a ring link network, each node can send data to any other node
directly without following a path.
In a ring link network, data is sent to all nodes simultaneously,
allowing for faster communication.
11. Interpret Technician A's statement regarding the absence of diagnostic
trouble codes during a Class 2 diagnosis check. What does it imply about
potential issues?
It confirms that all modules are communicating effectively.
It suggests that the wiring is intact.
It implies that there could be a communication problem.
It indicates that the module is functioning correctly.
12. What is the voltage level that indicates a logical '0' in UART communication?
5V
3.3 V
12 V
0V
Prep 2026 | Complete Question Bank | Latest Update |
1. hat is the primary benefit of twisting wires in differential BUS
communication?
to simplify installation
to reduce electromagnetic interference
to increase signal strength
to enhance data speed
2. If a vehicle is experiencing communication issues, how would you determine
whether the problem lies within the CAN or Class 2 system?
By checking the voltage levels and wiring configurations specific to
each communication protocol.
By analyzing the vehicle's fuel efficiency.
By replacing the OBD-II connector.
By inspecting the vehicle's model and year.
3. Describe how the characteristics of Controller Area Networks contribute to
vehicle communication systems.
Controller Area Networks are primarily used for data storage in
vehicles.
Controller Area Networks limit communication to only diagnostic
tools.
Controller Area Networks only connect a single device to the vehicle's
system.
, Controller Area Networks provide robust communication that allows
multiple devices to communicate efficiently in vehicles.
4. Describe how twisting wires in a differential BUS communication system
helps in maintaining signal integrity.
Twisting wires enhances the speed of data transmission significantly.
Twisting wires helps to cancel out electromagnetic interference,
thereby maintaining signal integrity.
Twisting wires increases the overall length of the communication line.
Twisting wires simplifies the installation process for technicians.
5. In a scenario where a vehicle's communication system is experiencing
interference, how would implementing differential BUS communication help
resolve the issue?
By minimizing the effects of electrical noise on the signal.
By simplifying the wiring configuration.
By increasing the number of wires used for communication.
By lowering the voltage levels in the system.
6. If a vehicle's Class A network is experiencing communication issues, which
type of application might be affected?
Non-critical vehicle functions such as interior lighting control
Engine management systems requiring real-time data
High-speed data applications for navigation systems
Safety systems like airbag deployment
,7. Describe the significance of the signal ground terminal in the OBD-II data link
connector.
The signal ground terminal is used for power supply to the OBD-II
connector.
The signal ground terminal is responsible for data transmission
between the vehicle and diagnostic tools.
The signal ground terminal connects to the vehicle's battery for
voltage regulation.
The signal ground terminal provides a common reference point for
all communication signals in the vehicle's diagnostic system.
8. Which terminal is designated for Class 2 communication in GM's data link
connector?
Terminal 4
Terminal 1
Terminal 2
Terminal 3
9. If a technician is unable to power their diagnostic tool using the OBD-II
connector, which pin should they check for connectivity issues?
Pin 4
Pin 16
Pin 1
Pin 5
, 10. Describe how a ring link network operates in terms of data transmission
between nodes.
In a ring link network, data travels in one direction around the
circle, passing through each node until it reaches its destination.
In a ring link network, data is transmitted in both directions, creating
redundancy.
In a ring link network, each node can send data to any other node
directly without following a path.
In a ring link network, data is sent to all nodes simultaneously,
allowing for faster communication.
11. Interpret Technician A's statement regarding the absence of diagnostic
trouble codes during a Class 2 diagnosis check. What does it imply about
potential issues?
It confirms that all modules are communicating effectively.
It suggests that the wiring is intact.
It implies that there could be a communication problem.
It indicates that the module is functioning correctly.
12. What is the voltage level that indicates a logical '0' in UART communication?
5V
3.3 V
12 V
0V
