ch 64
Which operating mode of the OBD II system shows pending DTC's? $1 $6 $3 $7
7
All of the following statements with respect to freeze-frame data are true except: Freeze-frame data are automatically recorded in the vehicle's PCM when a vehicle DTC is stored. Freeze-frame data are a list of sensor data that are associated with the specific DTC. Freeze-frame data is saved for all DTCs stored in memory. Difficult-to-find intermittent faults can be diagnosed by carefully reviewing the freeze-frame data for clues to the location of the fault.
Freeze-frame data is saved for all DTCs stored in memory.
Tech A says that on OBD II vehicles, it is a good idea to clear the codes before diagnosis and see if they reset. Tech B says that the DTC indicates which part needs to be changed. Who is correct?
neither
Tech A says that a CANbus network communicates over a bundle of many individual wires, specially designed for fast communication speed. Tech B says that OBD II mandates that a DTC must be set if the emissions are more than 1.5 times the EPA FTP. Who is correct?
tech b
Tech A says some mechanical engine problems can cause OBD II DTCs to be set. Tech B says that OBD II codes only monitor non-powertrain components. Who is correct?
tech a
Tech A says that monitors are designed to test whether emission systems are working properly. Tech B says that monitors are designed to store sensor data about a fault if a DTC is set. Who is correct?
tech a
Any of these may be required to diagnose a vehicle when diagnostic trouble codes (DTC's) have NOT been set EXCEPT: a digital oscilloscope. a smoke machine. a pressure gauge. an analog ohmmeter.
an analog ohmmeter
Tech A says that OBD I and OBD II DLC connectors are different from each other. Tech B says that OBD II standardizes the designations for diagnostic trouble codes (DTCs). Who is correct?
both
Tech A says that if the MIL is blinking, it indicates a catalyst-damaging fault. Tech B says that the EGR readiness monitor can use the MAP sensor to verify the EGR gases are flowing. Who is correct?
both
When misfires occur, the full volume of air and fuel from the misfiring cylinder is burned in the __________. EGR system Exhaust Catalyst Secondary air system
catalyst
Which of the following are used to make precise electrical measurements over time and display the results on a graph as a waveform? Digital storage oscilloscopes Scan tools Continuous monitors DMM
digital storage oscilloscopes
Which of the following is a continuous monitor? Fuel system monitor Catalytic converter monitor Evaporative system monitor EGR system monitor
fuel system monitor
A fault code that begins with the letter "B" would MOST likely address a fault in the: ignition system. exhaust system. taillight circuit. transmission.
taillight circuit
All of the following statements regarding DLC are true except: Scan tools serve to access OBD information via the DLC. Its location is also now fairly standardized as being within 2' of the engine. The DLC enables the scanner to access data stored in the vehicle's various computers. It is a 16-pin connector with a common (SAE J1962) size, shape, and pin layout.
Its location is also now fairly standardized as being within 2' of the engine.
Why is it important to run the monitors after repair? To ensure that the fault doesn't immediately reoccur. So that the vehicle will operate in closed loop. So that the vehicle will operate in open loop. To ensure that the PCM is updated to the latest software.
to ensure that the fault doesnt immediately reoccur
A diagnostic trouble code (DTC) indicates that a vehicle has experienced all of these EXCEPT: an emissions related fault. a broken "hard part." a set fault "code." an illuminated malfunction indicator lamp (MIL).
a broken hard part
Tech A says that the MIL can turn off if the fault doesn't reappear in three sequential trips. Tech B says that when an MIL is activated, the PCM stores the DTC until a predetermined number of drive cycles automatically erase the DTC or if cleared manually by a scan tool. Who is correct?
both
How can you make sure that the system isn't about to turn on the MIL due to pending codes? Checking the results of the monitors on Mode 6 and Mode 7 Reassembling the engine Erasing the codes Checking freeze-frame data
checking the results of the monitors on Mode 6 and 7
Open-loop electronic systems have become instrumental in cleaning up vehicle emissions in recent years.
false, its the closed loop system
Pending or current codes that have happened in the past but haven't been cleared manually with a scan tool, or automatically after approximately 40 warm-up cycles without the code reoccurring, are known as:
history codes
Tech A says that OBD II allows a technician to hook up a generic scan tool to read DTCs and clear DTCs. Tech B says that when the MIL is on, the vehicle should not be driven. Who is correct?
tech a
Tech A says that a "P" in the DTC stands for a powertrain code. Tech B says a "U" stands for an undetermined code. Who is correct?
tech a
Tech A says that monitors are designed to test if emission systems are working properly. Tech B says that monitors are designed to store sensor data about a fault if a DTC is set. Who is correct?
tech a
A graphing multimeter or a voltage meter is used to verify signals going to and from electrical and electronic components.
true
