Deck 4: On-Board Diagnostic Scanners and Digital Storage Oscilloscopes

Question 1

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

Answer 1

True

Question 2

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

Answer 2

C

Question 3

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

Answer 3

False

Question 4

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 5

While discussing scan testers: Technician A says scan testers 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 6

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 7

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

Question 8

Repeat component failures may be caused by a defective voltage suppression diode in a relay.

Question 9

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 10

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

Question 11

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 12

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

Question 13

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

Question 14

The PCM monitors exhaust temperatures to detect cylinder misfires.

Question 15

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

Question 16

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 17

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

Question 18

Technician A says all computer system problems can be solved by using a scan tester. 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 19

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 20

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

Question 21

On a DSO screen, what value is displayed vertically?

Question 22

What is LTFT and STFT?

Question 23

On a DSO screen, what value is displayed horizontally?

Question 24

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

Question 25

What is the basic function of all scan tools?

Question 26

What type of signal is always on or off?

Question 27

On an OBD II emission control system, how many oxygen sensors are required?

Question 28

How does the PCM determine catalyst efficiency?

Question 29

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

Question 30

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

Question 31

What are the advantages of the high-end OBD II scan tool compared to a code reader?

Question 32

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

Question 33

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

Question 34

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

Question 35

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?