Deck 4: On Board Diagnostic Scanners and Digital Storage Oscilloscopes

Question 1

An analog scope is less complicated and cheaper than a DSO (digital) scope.

Answer 1

True

Question 2

While discussing digital signals: Technician A says the leading edge of a digital signal represents a decreasing voltage. Technician B says duty cycle is the frequency at which a voltage signal occurs. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Answer 2

D

Question 3

While discussing the misfire monitor: Technician A says while detecting a Type B misfire, the monitor checks cylinder misfiring over a 1,000 rpm period. Technician B says while detecting a Type A misfire, the monitor checks cylinder misfiring over a 50 rpm period. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Answer 3

A

Question 4

On an OBD II emission control system, both pre-catalyst and post-catalyst oxygen sensors are used.

Question 5

Technician A says diagnostic scan tester operation varies depending on the make and model of the scan tool. Technician B says one of the major differences between OBD II and OBD I scan tools is how and where they are connected to the DLC. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 6

A technician is viewing a scan tool data stream to diagnose an OBD II system. The downstream HO₂S has the same voltage switching rate as the upstream HO₂S. Technician A says the air/fuel ratio is too rich. Technician B says the catalytic converter may be defective. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 7

Technician A says all computer system problems can be solved by using a scan tool. Technician B says many computer-controlled components can be tested with an ohmmeter or voltmeter. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 8

While discussing scan tools: Technician A says scan tools have the capability to diagnose various computer systems on a vehicle. Technician B says scan testers have the capability to display data and DTCs and perform many other diagnostic functions. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 9

The CAN protocol will never be a required protocol for all manufactured vehicles.

Question 10

The PCM monitors exhaust temperatures to detect cylinder misfires.

Question 11

The DSO sampling time is at least 20 times faster than other automotive testers.

Question 12

While discussing LTFT and STFT when the STFT number is -20 and the LTFT number is -20: Technician A says these numbers indicate the PCM is trying to decrease fuel delivery. Technician B says these numbers indicate a normal condition. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 13

Beginning in 1996, ODB II vehicles were equipped with a standard 18-pin DLC.

Question 14

Diagnostic scan tester operation varies depending on the make and model of the scan tool.

Question 15

While discussing the catalyst efficiency monitor: Technician A says if a fault occurs in the catalyst monitor system on three drive cycles, the MIL is illuminated. Technician B says if the catalytic converter is not reducing emissions properly, the voltage frequency increases on the upstream HO₂S. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 16

By referring to STFT and LTFT values, the technician can determine how the PCM is reacting to current engine operating conditions.

Question 17

While discussing OBD II systems: Technician A says if a misfire condition threatens engine or catalyst damage, the PCM flashes the MIL. Technician B says the PCM illuminates the MIL if a defect causes emission levels to exceed 1.5 times the emission standards for that model year. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 18

An OBD II scan tool generally offers greater control and more in-depth service information than was available to the service technician with earlier-generation systems and tools.

Question 19

If everything in the system is functioning smoothly, both LTFT and STFT values should be close to 0.

Question 20

While discussing digital storage oscilloscopes: Technician A says the DSO shows the signals as they occur. Technician B says the DSO reads signals, stores them, and then displays them. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 21

What are LTFT and STFT?

Question 22

On an OBD II emission control system, are the oxygen sensors placed upstream or downstream from the catalyst?

Question 23

On a DSO screen, what will happen if the time base selected is too long and the voltage range is set too high for the circuit being tested?

Question 24

What selection tells the DSO when to begin displaying a waveform?

Question 25

What type of data is stored while a DTC is being set?

Question 26

On a DSO screen, what value is displayed horizontally?

Question 27

What features are included in an enhanced OBD II diagnostic scan tool and what do they allow the technician access to?

Question 28

What is the basic function of all scan tools?

Question 29

On a DSO screen, what value is displayed vertically?

Question 30

What type of signal has a varying voltage within a specified range over a period of time?

Question 31

How does the PCM determine catalyst efficiency?

Question 32

What was the major difference in connecting an OBD II and a pre-OBD II scan tool?

Question 33

What term is used to represent the highest point in one cycle of an AC voltage waveform?

Question 34

What type of signal is always on or off?

Question 35

What are the advantages of the high-end OBD II handheld scan tools?