Automotive Repair Technician 5 : Engine

Automotive Repair Technician 5 : EngineDiagnostics

Lesson 4 Overview

In this lesson, you'll cover

onboard diagnostics

generation II (OBD-II),

which is a federally-

mandated diagnostic

process. The lesson also

guides you through

strategy-based diagnosis,

a scientific process of

elimination that can be used for all components and systems in an

automobile.

4.1 Describes onboard diagnostics generation II (OBD-II), which is a federally- mandated diagnostic processEngine Diagnosis

READING ASSIGNMENT

Read this assignment. Then read Chapter 87 in your textbook.

OBD II Onboard Diagnosis Generation-II

Page 1Copyright Penn Foster, Inc. 2019 Course Version: 1

Chapter 87 discusses the purpose and function of OBD-II systems

and lists the various continuous and noncontinuous monitors. The

chapter also explains the information that can be obtained from an

onboard diagnostics monitor, the criteria to enable an OBD monitor,

and the numbering designation of OBD-II diagnostic trouble codes.

The following videos and animation links from the author’s website will

help you better understand the textbook and your assignments.

OBD-II (www.jameshalderman.com/links/book_at/vid/ch82/video_

frame.html)

Diagnostic Trouble Code (DTC) (jameshalderman.com/links/a8/ht

ml5/DTC.html)

Retrieving Trouble Codes, Code Reader (jameshalderman.com/li

nks/a8/html5/retrieving_trouble_codes_reader.html)

Search the Internet to learn more about the history and rationale

behind OBD-II systems. What can you find out about OBD-I?

When operating on rough roads, certain 1996 and 1997 OBD-II

vehicles signal a “misfire” DTC. The misfire monitor in these vehicles

is very sensitive and can misinterpret slight crankshaft-speed

variations as ignition misfires.

Checking OBD II Monitor Status

This exercise will require the scan tool that you were encouraged to

rent or buy in an earlier exercise. Following the scan tool’s


http://www.jameshalderman.com/links/book_at/vid/ch82/video_frame.html

http://jameshalderman.com/links/a8/html5/DTC.html

http://jameshalderman.com/links/a8/html5/retrieving_trouble_codes_reader.html

instructions, check the status on all of your vehicle’s OBD-II monitors

and ensure that they’re running correctly.

Key Points and Links

READING ASSIGNMENT

Key Points

Depending on the powertrain control module’s (PCM’s)

determination of a misfire’s severity, the misfire monitor may set

a pending code until ignition is cycled off and the engine is

operated a second time.

Always perform a careful visual inspection of the area

surrounding the suspected problem area before proceeding with

a diagnostic testing.

Be sure the DMM you use isn’t autoranging; otherwise, when the

meter switches ranges, this can easily be mistaken as a glitch in

a sensor.

Links

OBD-II (www.jameshalderman.com/links/book_at/vid/ch82/video_

frame.html)

Diagnostic Trouble Code (DTC) (jameshalderman.com/links/a8/ht

ml5/DTC.html)

Retrieving Trouble Codes, Code Reader (jameshalderman.com/li

nks/a8/html5/retrieving_trouble_codes_reader.html)



http://jameshalderman.com/links/a8/html5/DTC.html

http://jameshalderman.com/links/a8/html5/retrieving_trouble_codes_reader.html

Engine Fuels

1. The powertrain control module (PCM) performs active and

intrusive tests of the components if the operating conditions of

the vehicle match the _______.

2. A _______ DTC is fuel- or misfire-related and will cause the

malfunction indicator lamp (MIL) to be turned on the first trip.

3. A _______ DTC will turn on the MIL after the second consecutive

trip.

4. _______ is a trip in which the engine temperature increases at

least 40 °F and reaches at least 160 °F (71 °C).

5. The _______ will flash if a misfire or fuel trim condition exists that

can cause damage to the catalytic converter.

6. A freeze-frame is generated on an OBD-II vehicle _______.

a. when a type C or D DTC is set.

b. when a type A or B DTC is set.

c. on every other trip.

d. if the PCM detects a problem with the O2S.

7. An ignition misfire or fuel-mixture problem is an example of what

type of DTC?

a. Type A

b. Type B

c. Type C

d. Type D

8. The comprehensive component monitor checks computer-

controlled devices for _______.


a. opens.

b. rationality.

c. shorts-to-ground.

d. all of the above.

9. OBD-II has been on all passenger vehicles in the United States

since _______.

a. 1986.

b. 1991.

c. 1996.

d. 2000.

Exercise Answer Key:

Engine Fuels

1. enabling criteria

2. type a

3. type b

4. Warm-up cycle

5. MIL

6. b

7. a

8. d

9. d


4.2 Identify strategy-based diagnosis, a scientificprocess of elimination that can be used for allcomponents and systems in an automobileDiagnosis Process and Scan Tool Diagnosis

READING ASSIGNMENT

Read this assignment. Then read Chapter 88 in your textbook.

Scan Tools and Engine Performance Diagnosis

Chapter 88 discusses the steps of the diagnostic process and the

types of scan tools that are used to assess vehicle components. It

explains procedures to follow if a diagnostic trouble code has been set

and the methods that can be used to reprogram (reflash) a vehicle

computer, along with the manufacturer’s diagnostic routines and the

procedures for resetting the computer.

The following videos and animation links from the author’s website will

help you better understand the textbook and your assignments.

Scan Tools and Engine Performance Diagnosis (www.jameshald

erman.com/links/book_at/vid/ch88/video_frame.html)

Scan Tool (jameshalderman.com/links/a1/html5/scan_tool.html)

Intermittent problems can be difficult to diagnose. Gather as much

information as possible for accurate diagnosis. Find out the

temperatures, speeds, and operating conditions present when

problems occur. Then try to duplicate the operating conditions and

cause the problem to occur yourself.



http://jameshalderman.com/links/a1/html5/scan_tool.html

Smoke machines can be used to find exhaust leaks. The tip of the

smoke machine is placed inside the tailpipe and, when the exhaust

system fills with smoke, any leaks will be obvious.

Creating a DTC and Checking It with a Scan Tool

This exercise will require a scan tool. First, review pages 971–973 of

your textbook. Then trigger a DTC on your vehicle by disconnecting

the engine coolant temperature sensor connector (black and yellow

wires). This should cause the check engine light (MIL) to light up. Use

the scan tool to determine what DTC was set; make a note of this DTC

for future reference. Then reconnect the sensor and use your scan

tool to erase the DTC.

Key Points and Links

READING ASSIGNMENT

Key Points

The best diagnostic resource is having the driver or owner of a

car explain to you how the drivability of the vehicle has been

affected.

Intermittent problems can be difficult to diagnose. It’s important to

gather as much information as possible for accurate diagnosis.

Find out the temperatures, speeds, and operating conditions

present when problems occur. Then try to duplicate these

operating conditions and cause the problem(s) to occur yourself.


Links

Scan Tools and Engine Performance Diagnosis (www.jameshald

erman.com/links/book_at/vid/ch88/video_frame.html)

Scan Tool (jameshalderman.com/links/a1/html5/scan_tool.html)

Engine Fuels

1. During a ________ the parameters are set for the PCM to

perform active tests to determine if the emissions control system

is functioning correctly.

2. A type A DTC indicates a misfire or fuel trim problem that could

damage the catalytic converter. A type B code is an emission-

related code that will be stored if a component or system fails on

________ consecutive trips.

3. A _________ can include checking for leaks, poor electrical

connections, fluid levels, air filters, and evidence of previous

repairs.

4. Technician A says that the first step in the diagnostic process is

to verify the problem or concern. Technician B says that the

second step is to perform a thorough visual inspection. _______

is/are correct.

a. Technician A

b. Technician B

c. Both Technicians A and B

d. Neither Technician A nor B



http://jameshalderman.com/links/a1/html5/scan_tool.html

5. Which item is not important to know before diagnosing an engine

performance problem?

a. List of previous repairs

b. Brand of engine oil used

c. Type of gasoline used

d. Temperature of the engine when the problem occurs

6. The preferred method for clearing DTCs is to _______.

a. disconnect the negative battery cable for 10 seconds.

b. use a scan tool.

c. remove the PCM power-feed fuse.

d. Cycle the ignition key on and off 40 times.

Exercise Answer Key:

Engine Fuels

1. drive cycle (or trip)

2. two

3. visual inspection

4. c

5. b

6. b

Lesson 4 Review


Self-Check

1. In OBD-II systems, what is the special software program

incorporated in powertrain control modules (PCMs) designed to do?

a. Manage the operation of all OBD-II monitors by detecting

malfunctions in equipment sensors.

b. Manage the operation of all OBD-II vehicles by monitoring the

California Air Resources Board (CARB) regulations

c. Manage the operation of all OBD-II monitors by controlling the

sequence of steps necessary to execute the diagnostic tests and

monitors

d. Manage the operation of all OBD-II systems and malfunction

indicator lamps (MILs) for rationality

2. Pablo is running diagnostic tests on a vehicle where an engine

misfire has been detected and the malfunction indicator lamp (MIL)

remains on. What type of misfire is occurring and what will happen?

a. Misfire type B, causing the vehicle to fail an inspection and

maintenance tailpipe emissions test

b. Misfire type A, causing the crankshaft position sensor (CKP) to

short out

c. Multiple misfire types A and B, causing a cylinder misfire

d. Misfire type A, causing catalyst damage

3. What is a warm-up cycle?

a. An exponentially weighted moving average (EWMA) monitor that

registers an engine temperature increase of at least 40°F

b. A trip that includes an engine temperature increase of at least

160°F and where engine temperature does not go below 40°F


c. A trip that includes an engine temperature increase of at least

40°F and where engine temperature reaches at least 160°F

d. An EGR test that includes an engine temperature increase of at

least 10°F and where engine temperature reaches at least 40°F

4. Arabella wants to run a drive cycle where the powertrain control

module (PCM) looks at a series of data points representing speed and

time and determines when the right conditions to perform a monitor or

a test of a component. What common conditions must Arabella have

in place to run the drive cycle in most vehicles?

a. Each vehicle requires its own manufacturer-specific conditions for

a drive cycle

b. Cold start, fuel range from 15% to 85%, a known speed and time

range, and the ability to stop and idle for a certain time

c. Fuel at least 15%, a known speed and time range, an ECT of at

least 87°F, ability to stop and idle at will

d. Cold start, fuel range at least 85%, 22 minutes to run vehicle at

no less than 30 mph, and the ability to stop and idle for at least 10

minutes

5. The powertrain control module (PCM) will turn off the malfunction

indicator lamp (MIL) when the codes are cleared with a scan tool and

when power to the PCM is removed at the battery or with the PCM

power fuse for an extended period of time. What is the other condition

under which the PCM will turn off the MIL?

a. When a vehicle is driven on three consecutive trips with a warm-

up cycle and meets all code set conditions without the PCM detecting

any faults


b. When the comprehensive component monitors (CCMs) run on

three consecutive trips with a warm-up cycle and meet all code set

conditions without the PCM detecting any faults

c. When a vehicle is driven once with a warm-up cycle and meets

all code set conditions without the PCM detecting any faults

d. When the PCM concludes three drive cycles and all set code

conditions are met

6. A customer alerts Damian that the service engine soon alert light in

his vehicle is turned on. What type of diagnostic trouble codes (DTCs)

should Damian be looking for?

a. Type A codes only

b. Type A and B codes

c. Type A, B, and D codes

d. Type C and D codes

7. Randy is having trouble clearing the diagnostic trouble codes

(DTCs) from a vehicle he is working on. He thinks he has resolved all

the issues, so he considers disconnecting the battery to reset the

DTCs. What should Randy do?

a. Randy should disconnect the battery and reset all the learned

engine operating parameters.

b. Randy should wait for the computer to clear the DTC after 40

consecutive warm-up cycles with no further faults detected and then

use the diagnostic scan tool to verify no additional faults are detected.

c. Randy should make sure the diagnostic procedure has cleared

the fault and directed him to reset the DTC, and then he should

disconnect the battery even though memory for the radio and other


learned engine operating parameters will be lost.

d. Randy should make sure the diagnostic procedure has cleared

the fault and directed him to reset the DTC, and then he should wait

for the computer to clear the DTC after 40 consecutive warm-up

cycles with no further faults detected.

8. What are the three types of powertrain control module (PCM) tests?

a. Open, shorts, and ground

b. Rationality, functionality, and electrical

c. EVAP purges, transmission controls, and operation outputs

d. Camshaft position sensors (CMPs), TP sensors, and

transmission controls

9. Mikala is using a scan tool that asks her for the make, model, and

year of the vehicle she is working on. Why does Mikala need to input

that information?

a. The scan tool must access the correct information about the

vehicle to reset the diagnostic trouble codes (DTCs).

b. The scan tool must access factory information to verify the

diagnostic codes.

c. The scan tool is accessing the factory or enhanced part of the

powertrain control module (PCM).

d. The scan tool is accessing the generic or global part of the


10. Donny is using Mode 6 to diagnose faults. He has checked the

monitor status to determine how the system failed, and he has

examined the component that triggered the fault to help discover the

root of the problem. What is Donny's next step?


a. Donny should run the three powertrain control module (PCM)

tests.

b. Donny should check to see what malfunction indicator lamps

(MILs) turn on intermittently.

c. Donny should look at the monitor enable criteria to determine

what it takes to fail or pass the monitor.

d. Donny should enter the vehicle's make, model, and year into the

scan tool to determine the diagnostic trouble code (DTC).

11. Determining whether a malfunction indicator lamp (MIL) is on, if

the engine was hot or cold, at what point the problem occurred, and

how far the vehicle was driven are all part of which step in the eight-

step diagnostic procedure?

a. Step 8

b. Step 6

c. Step 1

d. Step 4

12. Lizzie checks a vehicle for fuel leaks, problems with hoses, and

corroded connectors. What step in the eight-step diagnostic procedure

is Lizzie performing?

a. Step 2

b. Step 4

c. Step 3

d. Step 1

13. Why should you thoroughly inspect both original-equipment and

aftermarket parts?

a. Many people believe that only small aftermarket parts such as


hoses and connectors work better than original-equipment parts, so

it's best to check all the parts.

b. Many people believe original-equipment parts work better than

aftermarket parts , but original-equipment parts have been known to

fail early in their service life.

c. Many people believe aftermarket parts work better than original-

equipment parts, but aftermarket parts have been known to fail early

in their service life.

d. Many people believe that only original-equipment parts are built

to endure long term, but aftermarket parts are known for having a

longer service life.

14. A customer tells Kate that his vehicle seems to be having various

problems, but no check engine or other malfunction indicator lamp

(MIL) has turned on. Kate runs a diagnostic scan, which returns

several diagnostic codes that indicate something is wrong with the

vehicle. What are these codes called and what do they mean?

a. The codes are no-fault codes (NFCs), and they indicate the

problems the customer is experiencing are part of minor wear and tear

on the vehicle.

b. The codes are pending codes, and they indicate that the fault

has not repeated to cause the powertrain control module (PCM) to

turn on the MIL.

c. The codes are further testing codes (FTCs), and they indicate the

powertrain control module (PCM) should have turned on the MIL, but

the MIL is not functioning.

d. The codes are diagnostic trouble codes (DTCs), and they


indicate the fault is not a high enough priority to trigger the powertrain

control module (PCM) to turn on the MIL.

15. A customer describes a problem with her vehicle to Khalid, who

remembers seeing information about the same symptoms in a

technical service bulletin (TSB) from the manufacturer. Khalid is sure

he knows what the problem is. What should Khalid do next?

a. Khalid should ignore the TSB and perform the repairs based on

standard diagnostic procedures.

b. Khalid should direct the customer to contact the manufacturer for

more information on getting her vehicle repaired.

c. Khalid should locate the TSB and perform the repairs the TSB

suggests.

d. Khalid should perform a scan to retrieve the correct diagnostic

trouble codes (DTCs).

16. When reviewing scan tool data in diagnostic step five, you should

consider the information provided in a definite sequence with specific

data that will tell you the most about the engine's operation. The data

should include information such as whether the engine coolant

temperature (ECT) is the same as the intake air temperature (IAT)

after the vehicle sits for a few hours and that the idle air control (IAC)

valve is being commanded to an acceptable range. What other key

piece of information should you look for?

a. That the transmission sensor is operating with readings below

100 mV at times, readings above 500 mV at times, and that there are

rapid transitions between rich and lean

b. That the malfunction indicator lamp (MIL) is functioning, which


means it should light when a fault is detected in the engine multiple

times

c. That the diagnostic trouble codes (DTCs) for the engine operation

match with any symptoms or issues described by the customer

d. That the oxygen sensor is operating with readings below 200 mV

at times, readings above 800 mV at times, and that there are rapid

transitions between rich and lean

17. In Step 6 of the eight-step diagnostic procedure, what is one

method that you could use to narrow the diagnostic focus to a system

or individual cylinder?

a. Perform a general systems check.

b. Perform a visual inspection test.

c. Perform an oxygen sensor test.

d. Perform a cylinder power balance test.

18. Shelly's repair shop insists that all technicians follow the eight-step

diagnostic procedure to ensure repairs are made well and the

customer is satisfied. Shelly has completed steps one through six, and

is now working on Step 7. What is Shelly doing?

a. Preparing a customer satisfaction survey to gain valuable

feedback on the service aspects of the repair process

b. Repairing and replacing parts according to the manufacturer's

recommendation and ensuring that she has found the root cause of

any problems

c. Reviewing all diagnostic trouble codes (DTCs) and ensuring that

the root cause of each code has been identified

d. Performing a compression and cylinder leakage test to determine


the probable root cause of any problems

19. Gerry is performing the final step in the eight-step diagnostic

procedure. Gerry has test driven the vehicle and checked to make

sure no additional problems occurred during the repair procedure. He

has also cleared the diagnostic trouble codes (DTCs). Why is it

important for Gerry to clear the DTCs?

a. Because the powertrain control module (PCM) can only store so

much information and must be regularly cleared of DTCs after repairs

are completed

b. Because the stored DTCs will continue to trigger the malfunction

indicator lamps (MILs) even though the problems are all resolved

c. Because clearing the DTCs ensures the computer won't make

any changes based on a stored DTC

d. Because the vehicle must now be tested for emissions and the

monitors will need to be run and pass

20. What are the five steps for retrieving diagnostic information from

the powertrain control module (PCM) using a diagnostic scan tool?

a. Locate and access the data link connector (DLC), connect the

scan tool to the DLC and establish communication, follow the on-

screen instructions to correctly identify the vehicle, observe the scan

data and any diagnostic trouble codes (DTCs), and follow the

manufacturer's instructions or compare all sensor values with a factory

acceptable range chart.

b. Use the data link connector (DLC) to connect to the powertrain

control module (PCM), establish communication with a scan tool,

follow instructions to identify if the tool is a factory or generic scan tool,


observe the scan data and any diagnostic trouble codes (DTCs), and

compare all sensor values with a factory acceptable range chart.

c. Connect the scan tool to the DLC and establish communication,

perform multiple sensor checks including checking powertrain control

module (PCM), observe the scan data and any diagnostic trouble

codes (DTCs), perform a power cylinder balance test to help

determine the root cause of the problem, and follow the



d. Determine if the scan values are out of range, establish a

connection between the powertrain control module (PCM) and the

scan tool, follow the on-screen instructions to correctly identify the

vehicle, review any diagnostic trouble codes (DTCs), and follow the



Self-Check Answer Key

1. Manage the operation of all OBD-II monitors by controlling the


monitors

Explanation: In OBD-II systems, the special software program

incorporated in powertrain control modules (PCMs) is designed to

manage the operation of all OBD-II monitors by controlling the


monitors.


Reference: Section 4.1

2. Misfire type B, causing the vehicle to fail an inspection and

maintenance tailpipe emissions test

Explanation: Pablo is seeing a misfire type B where

the MIL illuminates steadily and a DTC is stored because the

firing event is over 1,000 revolutions, which exceeds the EPA

federal test procedure (FTP) standard by 1.5 times, causing the

vehicle to fail an inspection and maintenance tailpipe emissions

test.


3. A trip that includes an engine temperature increase of at least

40°F and where engine temperature reaches at least 160°F

Explanation: A warm-up cycle is a trip that includes an engine

temperature increase of at least 40°F and where engine

temperature reaches at least 160°F


4. Cold start, fuel range from 15% to 85%, a known speed and time

range, and the ability to stop and idle for a certain time

Explanation: To run a drive cycle, Arabella must have a cold start,

a fuel range from 15% to 85%, a known speed and time range,

and the ability to stop and idle for a certain time. Each vehicle will

have its own specifications, but these are common conditions for

most.



5. When a vehicle is driven on three consecutive trips with a warm-

up cycle and meets all code set conditions without the PCM

detecting any faults

Explanation: The other condition under which the PCM will turn

off the MIL occurs when a vehicle is driven on three consecutive

trips with a warm-up cycle and meets all code set conditions

without the PCM detecting any faults.


6. Type A and B codes

Explanation: Damian should be looking for type A and type B

codes, which are both exhaust emissions-related codes that

typically light up the check engine or service engine soon

malfunction indicator lamps (MILs).


7. Randy should make sure the diagnostic procedure has cleared

the fault and directed him to reset the DTC, and then he should

wait for the computer to clear the DTC after 40 consecutive

warm-up cycles with no further faults detected.

Explanation: Because disconnecting the battery may not reset

the DTCs and will likely lose all learned engine operating

parameters, Randy should make sure the diagnostic procedure

has cleared the fault and directed him to reset the DTCs. The


computer will clear the DTCs after 40 consecutive warm-up

cycles with no further faults.


8. Rationality, functionality, and electrical

Explanation: The three types of PCM tests are rationality, or

comparison of inputs; functionality, or inputs checking outputs;

and electrical, or a PCM check of both inputs and outputs.


9. The scan tool is accessing the factory or enhanced part of the


Explanation: Mikala needs to input the vehicle's make, model,

and year because the scan tool is accessing the factory, or

enhanced, part of the PCM. If the generic or global part of the

PCM is being scanned, then there is no need to know the vehicle

identification details.


10. Donny should look at the monitor enable criteria to determine

what it takes to fail or pass the monitor.

Explanation: When using Mode 6 information to diagnose

faults, Donny's next step should be to look at the monitor enable

criteria to determine what it takes to fail or pass the monitor.



11. Step 1

Explanation: Verifying the problem is the first step in the eight-

step diagnostic procedure. Before diagnosing or repairing a

problem, you must verify the problem exists and under what

conditions it occurs.


12. Step 2

Explanation: Lizzie is performing part of Step 2, which is to

perform a thorough visual inspection and basic tests. She is

checking for any obvious problems with the vehicle.


13. Many people believe aftermarket parts work better than original-

equipment parts, but aftermarket parts have been known to fail

early in their service life.

Explanation: Many people believe aftermarket parts work better

than original-equipment parts, but aftermarket parts have been

known to fail early in their service life. It's a good idea to inspect

all parts thoroughly and to not assume that a newer, aftermarket

part cannot fail or be the cause of a problem.


14. The codes are pending codes, and they indicate that the fault has

not repeated to cause the powertrain control module (PCM) to

turn on the MIL.


Explanation: The codes are pending codes, and they indicate that

the fault has not repeated to cause the powertrain control module

(PCM) to turn on the MIL. They let Kate know a fault has

occurred but more testing is needed to determine the root cause

of the issue.


15. Khalid should perform a scan to retrieve the correct diagnostic

trouble codes (DTCs).

Explanation: Before Khalid proceeds, he should retrieve the

correct diagnostic trouble codes (DTCs) for the vehicle by running

a scan. It's important to know the DTCs before performing any

repairs because bulletins often include information on solving

problems that involve a stored diagnostic trouble code.


16. That the oxygen sensor is operating with readings below 200 mV

at times, readings above 800 mV at times, and that there are

rapid transitions between rich and lean

Explanation: The third key piece of information you should look

for is that the oxygen sensor is operating with readings below 200

mV at times, readings above 800 mV at times, and that there are

rapid transitions between rich and lean.


17. Perform a cylinder power balance test.


Explanation: One method you could use in Step 6 is to perform a

cylinder power balance test. If a weak cylinder is detected, you

can then perform a compression and a cylinder leakage test to

determine the probable cause.


18. Repairing and replacing parts according to the manufacturer's

recommendation and ensuring that she has found the root cause

of any problems

Explanation: If she is following Step 7 of the eight-step diagnostic

procedure, Shelly is repairing and replacing parts according to

the manufacturer's recommendation and ensuring that she has

found the root cause of any problems.


19. Because clearing the DTCs ensures the computer won't make

any changes based on a stored DTC

Explanation: It's important for Gerry to clear the DTCs because

doing so ensures the computer will not make any changes based

on a stored DTC. However, if Gerry needed to test the vehicle for

emissions, he should not yet clear the DTCs, as all the monitors

must be run and pass.


20. Locate and access the data link connector (DLC), connect the

scan tool to the DLC and establish communication, follow the on-


screen instructions to correctly identify the vehicle, observe the

scan data and any diagnostic trouble codes (DTCs), and follow

the manufacturer's instructions or compare all sensor values with

a factory acceptable range chart.

Explanation: The steps for retrieving diagnostic information from

the PCM using a scan tool are:

1. Locate/access the DLC.

2. Connect the scan tool to the DLC; establish communication.

3. Follow the on-screen instructions to identify the vehicle.

4. Observe the scan data and any DTCs.

5. Follow the manufacturer's instructions/compare sensor

values to range chart.


Flash Cards

1. Term: Powertrain Control Modules (PCMs)

Definition:

Performs active and intrusive tests of the components to determine if

the operating conditions of the vehicle match the enabling criteria

2. Term: OBD-II-equipped Vehicle

Definition: Able to detect component degradation or a faulty

emission-related system that prevents compliance with federal


emission standards

3. Term: Monitor

Definition: General name for an organized method of testing a

specific part of the system that the computer performs to evaluate

components and systems

4. Term: Malfunction Indicator Lamp (MIL)

Definition: An instrument panel warning lamp able to alert the driver

of certain control system failures

5. Term: Trip

Definition: A key-on condition that contains the necessary conditions,

called the enable criteria, for a particular test to be performed,

followed by a key-off

6. Term: Drive Cycle

Definition: The powertrain control module (PCM) looks at a series of

data points representing speed and time and determines when the

conditions are right to perform a monitor or test of a component

7. Term: Pending Codes

Definition: Codes that are set when operating conditions are met and

the component or circuit is not within the normal range, yet the

conditions have not yet been met to set a DTC


8. Term: Comprehensive Component Monitor (CCM)

Definition: Constantly compares sensor values with known good

values stored in the PCM’s memory to monitor a failure in any

electronic component or circuit

9. Term: Rationality Test

Definition: A test where the input signal is compared against other

inputs and information to see if it makes sense under the current

conditions

10. Term: Functionality Test

Definition: A test where PCM inputs check the operation of the

outputs

11. Term: Diagnostic Trouble Codes (DTCs)

Definition: Stored codes that have five characters indicating the

problem area, vehicles covered, area of the problem, and the section

12. Term: Flash Codes

Definition: A diagnostic method in which the MIL will flash to indicate

diagnostic trouble codes (DTCs)

13. Term: Data Link Connector (DLC)

Definition: A standardized 16-cavity connector where a scan tool can

be connected to retrieve diagnostic information from a vehicle’s

computers


14. Term: Electronically Erasable Programmable Read-only Memory

(EEPROM)

Definition: A component of the powertrain control module (PCM) that

can be reprogrammed through remote, direct, or off-board

programming by downloading new calibration files from a scan tool,

personal computer, or modem

15. Term: Technical Service Bulletins (TSBs)

Definition: Correction or repair procedures provided by automobile

manufacturers that often include information on solving problems that

involve a stored diagnostic trouble code

16. Term: Freeze-frame

Definition: A snapshot of important engine data at the time the

diagnostic trouble code (DTC) was set


Automotive Repair Technician 5 : Engine

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