Exam 12: Multiplexing

Technician A says that processors networked to J1939 data bus must have clock speeds of at least 16 MHz.Technician B says that a frequency of 16 MHz translates into a capability of making 16,000 binary decisions per second.Who is correct?

Technician A says that if one terminating resistor was missing from a J1939 data bus,it would likely function without problems.Technician B says that if both terminating resistors were missing from a chassis data bus,no data transactions would be possible.Who is correct?

Three of the following mean the same thing.Which is the odd one out?

Technician A says that field effect transistor (FET)is commonly used in multiplexed circuits to act like an electronic relay switch.Technician B says that an advantage of FETs is that gate channel resistance is so high there is almost no current flow in the gate.Who is correct?

Which of the following methods are used to access diagnostic codes from a controller with an address on a truck data bus?

What is another way of saying smart switch?

Technician A says that some OEMs permit physical repairs on high bus wiring providing guidelines in their service literature are observed.Technician B says that low bus wiring can never be repaired once damaged.Who is correct?

What type of data connector is required to access a SAE J1939 data bus?

What is the maximum permissible,physical length of a J1939 data bus?

What term is used to describe the volume of data that can be handled on a data bus?

Technician A says that there can be up to 2 open Tees on a J1939 data backbone.Technician B says that most truck data backbones use electrical pressures of around 5 volts.Who is correct?

What is the characteristic impedance of a J1939 data bus?

What field in a data packet is used to define the urgency of a broadcast over the data bus?

Technician A says that HH-ESTs,OEM software,and a DLC can be used to access a J1939 data bus.Technician B says that a generic HH-EST loaded with a general heavy duty reader software can be used to program customer data to controller modules on the data bus.Who is correct?

What is used to circuit protect FET switched headlamp and electric wipers in a typical multiplex chassis?

Which of the following DLCs is required to access J1939 on a Volvo-Mack chassis MY 2014 or later?

Technician A says that a scopemeter can help technicians interpret hexadecimal code for troubleshooting purposes.Technician B says that a labscope may help to identify a non-communicating node (controller)on the buse.Who is correct?

If the J1939 connection was lost,how would the driver of the vehicle know this had occured?

Technician A says that a black J1939 9-pin DLC can be connected to a green J1939 9-pin receptacle.Technician B says that a green J1939 9-pin DLC can be connected to a black J1939 9-pin receptacle.Who is correct?

What is the maximum permitted length of an stub extending from a J1939 data bus?