Question 1

A generic (global)-type scan tool can retrieve ________ data.

Accepted Answer

C

Question 2

The steps in a manufacturer-specific diagnostic routine are being discussed. Technician A says that after recording any DTCs, the codes should be erased. Technician B says to road test the vehicle twice to turn off the MIL. Which technician is correct?

Accepted Answer

C

Question 3

What fault could occur that can cause a driveability issue and not set a diagnostic trouble code (DTC)?

Accepted Answer

Each of the listed issues (contaminated fuel, clogged air intake systems, and high concentrations of ethanol in the fuel) can cause driveability problems without necessarily triggering a diagnostic trouble code (DTC), as they may not be directly monitored by the vehicle's onboard diagnostic system.

Question 4

A drive cycle is designed to reset all the OBD-II monitors. Before starting the drive cycle the engine should be ________.

Accepted Answer

A drive cycle typically begins with a cold engine (ECT = IAT), which allows the vehicle's onboard diagnostics (OBD-II) system to properly run through all of its checks and balances from a consistent starting point.

Question 5

How many steps does the book outline for a systematic diagnostic procedure?

Accepted Answer

The book outlines eight steps for a systematic diagnostic procedure.

Question 6

What is the first step of the diagnosis process?

Accepted Answer

Before diagnosing a vehicle, it is important to verify the problem through customer complaints or your own observations. This ensures that you are addressing the correct issue and not wasting time or money on unnecessary repairs. Once the problem is verified, then the diagnostic process can proceed with retrieving diagnostic trouble codes, looking at scan tool data, and checking for technical service bulletins.

Question 7

All these actions involve verifying the problem EXCEPT ________.

Accepted Answer

The answer of All these actions involve verifying the problem...

Question 8

Technician A says that it is a good idea to perform a test drive before attempting repairs. Technician B says that its a good idea to let the customer accompany the technician on the test drive. Which technician is correct?

Accepted Answer

Technician A is correct because performing a test drive can help to identify the issue and also ensure that the repair has been successful. Technician B is also correct because letting the customer accompany the technician on the test drive can help to build trust with the customer and provide them with a better understanding of the issue and the repair.

Question 9

Technician A assumes a replacement part is good just because it is new. Technician B says that sometimes recent repair work will be the cause of a complaint. Which technician is correct?

Accepted Answer

Technician B is correct that recent repair work can sometimes be the cause of a complaint. Technician A is incorrect to assume that a replacement part is automatically good just because it is new. The part could be faulty or may not be the correct part for the vehicle.

Question 10

Which diagnostic step is the most important aspect of diagnosis?

Accepted Answer

The answer of Which diagnostic step is the most important...

Question 11

Technician A says that when checking engine oil, it is normal for the oil to catch fire if lit by a match. Technician B says that oil on the dipstick that catches fire when lit is a sign of fuel in the oil. Which technician is correct?

Accepted Answer

Technician B is correct because engine oil catching fire when exposed to a flame is not normal and indicates contamination, such as fuel in the oil, which can lower its flash point and make it more flammable.

Question 12

Technician A says to check coolant level in the radiator when it is hot. Technician B says to check coolant level in the radiator when it is cool. Which technician is correct?

Accepted Answer

Technician B is correct. Coolant level should be checked when the engine is cool to prevent burns or injury from hot coolant or steam. Checking the coolant level when the engine is hot can also give a false reading due to expansion of the coolant.

Question 13

Technician A says that water floats to the top of fuel in the tank. Technician B says that water is more likely to be drawn into the system when the fuel level is low. Which technician is correct?

Accepted Answer

Technician B is correct. Water is more likely to be drawn into the fuel system when the fuel level is low because the fuel pickup tube is closer to the bottom of the tank where water can accumulate. Technician A is incorrect because water actually sinks to the bottom of the tank, where it can cause corrosion and damage to the fuel system.

Question 14

Technician A says that low battery voltage can cause driveability problems. Technician B says that the charging voltage should be over 15 volts when the engine is idling. Which technician is correct?

Accepted Answer

Technician A is correct. Low battery voltage can cause driveability problems as it affects the functioning of various electrical components in the vehicle. Technician B is incorrect as the charging voltage should be between 13.5 to 14.5 volts when the engine is idling. A voltage over 15 volts indicates overcharging, which can damage the battery and other electrical components.

Question 15

Technician A says that a standard spark plug can be used to check proper ignition system voltage. Technician B says that the energy required to jump the gap of a spark tester is around 3000 volts. Which technician is correct?

Accepted Answer

A standard spark plug cannot accurately check proper ignition system voltage because it does not simulate the conditions under which the ignition system operates under load. The energy required to jump the gap of a spark tester is typically higher than 3000 volts, often around 10,000 to 25,000 volts or more, depending on the system.

Question 16

Technician A says that a vehicle may have stored DTCs even if the MIL is not illuminated. Technician B says that all DTCs will illuminate the MIL. Which technician is correct?

Accepted Answer

Technician A is correct. A vehicle may have stored Diagnostic Trouble Codes (DTCs) even if the Malfunction Indicator Lamp (MIL) is not illuminated. The MIL will only illuminate for certain codes that are considered emissions-related or safety-related, but there may be other codes stored in the system that do not trigger the MIL. Technician B is incorrect because not all DTCs will cause the MIL to illuminate.

Question 17

Technician A says that most TSBs involve a specific stored DTC. Technician B says that the ECT and IAT reading should be close to the same temperature after the vehicle sits for several hours. Which technician is correct?

Accepted Answer

Most Technical Service Bulletins (TSBs) do indeed involve a specific stored Diagnostic Trouble Code (DTC), as they are often issued to address common issues found in particular models, which can include specific fault codes. Technician B is correct because the Engine Coolant Temperature (ECT) sensor and the Intake Air Temperature (IAT) sensor should read similarly after the vehicle has been off for a few hours, reflecting the ambient temperature, indicating both sensors are functioning correctly.

Question 18

Technician A says that a power balance test is the best way to isolate the problem cylinder. Technician B says that a compression and cylinder leakage test can help determine the cause of the problem. Which technician is correct?

Accepted Answer

Both technicians A and B are correct.

Technician A is correct in stating that a power balance test is the best way to isolate the problem cylinder. During a power balance test, the engine's computer is used to cut out the fuel or spark to each cylinder one at a time, and the change in RPM is noted. If there is no change in RPM when a particular cylinder's fuel or spark is cut, it means that cylinder is not contributing to the engine's power output, indicating a problem with that cylinder.

Technician B is also correct in stating that compression and cylinder leakage tests can help determine the cause of the problem. These tests can help identify issues such as low compression, worn piston rings, leaking valves, or blown head gaskets - all potential causes of a misfiring or non-contributing cylinder.

Question 19

Technician A says that a symptom may be corrected without correcting the cause of the problem. Technician B says that verifying the repair will determine if the root cause of the problem has been repaired. Which technician is correct?

Accepted Answer

Technician A is correct. Sometimes symptoms can be temporarily corrected without fixing the root cause of the problem.
Technician B is also correct. The only way to confirm if the problem has been fixed is by verifying if the symptoms have disappeared and if the root cause has been repaired.

Question 20

When should DTCs be cleared?

Accepted Answer

DTCs should only be cleared after the repair has been verified. Clearing the codes before verifying the repair can cause confusion and make it difficult to determine if the repair was successful. It is important to make sure the vehicle is running properly and the issue has been resolved before clearing the codes.

Quiz 1: The Diagnostic Process

A generic (global) -type scan tool can retrieve ________ data.