M12 CHAPTER 12 ON BOARD DIAGNOSTICS (OBDII)
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AND COMPUTER SYSTEMS EXAM QUESTIONS AND
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ANSWERS
Adaptive strategy - g g
ANSWER The ability of a computer to adapt to certain defects in the system.
g g g g g g g g g g g g g g
Calibration - ANSWER A set of instructions programmed into the PCM or
g g g g g g g g g g g
contained on a PROM that tailors the PCM to the vehicle.
g g g g g g g g g g
Catalyst efficiency monitor -
g g g
gANSWER A monitor in OBD II systems that checks the oxygen content of the e
g g g g g g g g g g g g g g
xhaust before it enters the catalytic converter and after it leaves the converter.
g g g g g g g g g g g g
Comprehensive component monitor (CCM) - g g g g
gANSWER One of the monitor systems in an OBD II system that checks the act
g g g g g g g g g g g g g g
ivity and efficiency of several systems and major components.
g g g g g g g g
Cylinder misfire monitoring - g g g
ANSWER crankshaft speed acceleration as each cylinder fires.
g g g g g g g g
Drive cycle - ANSWER A specified set of driving conditions. The drive cycle
g g g g g g g g g g g g
is important to adaptive strategies of a computer. The proper drive cycle is also
g g g g g g g g g g g g g
required of OBD II systems to complete monitor tests on certain systems.
g g g g g g g g g g g
Electronically erasable programmable read only memory (EEPROM) -g g g g g g g
ANSWER A computer chip that may be easily erased and reprogrammed with s
g g g g g g g g g g g g g
pecial equipment.
g
Enable criteria - g g
gANSWER Conditions that must be met before the PCM can initiate a test of a co
g g g g g g g g g g g g g g g
mponent or system. These criteria are specific to the sensor or system being teste
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d.
Failure record - ANSWER Some manufacturers such as GM have provided
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more than one freeze frame known as "failure records." See freeze frame.
g g g g g g g g g g g
,Flashing - g
gANSWER A term that is used to describe programming an OBD II PCM.
g g g g g g g g g g g g
Fuel system monitor - ANSWER A monitor that checks short- and long-
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term fuel corrections during closed loop.
g g g g g
Heated oxygen sensor - g g g
gANSWER A sensor that is electrically heated to accurately sense exhaust
g g g g g g g g g g g
gases regardless of operating temperature.
g g g g
Information retrieval - g g
gANSWER Refers to the microprocessor retrieving information from some
g g g g g g g g g
of the computer memories.
g g g
Information storage - ANSWER Refers to the microprocessor sending
g g g g g g g g
information to some of the memories where it is stored for future reference.
g g g g g g g g g g g g
Keep alive memory (KAM) -
g g g g
gANSWER The microprocessor can read information from the KAM but it cann
g g g g g g g g g g g
ot write information into this chip. KAM memory is retained when the ignition s
g g g g g g g g g g g g g
witch is turned off, but it is erased when battery power is disconnected from the c
g g g g g g g g g g g g g g g
omputer.
Long-term fuel trim (long-term FT) - ANSWER Moves slowly to keep short-
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term fuel trim near zero.
g g g g g
Microprocessor - ANSWER The decision-making chip in a computer. g g g g g g g g
Parameter identification (PID) - g g g
gANSWER A mode that allows access to certain data. g g g g g g g g
Programmable read only memory (PROM) - g g g g g
gANSWER A computer chip containing some of the computer program. This
g g g g g g g g g g
chip is removeable in some computers.
g g g g g g
Random access memory (RAM) - g g g g
gANSWER A computer chip that the microprocessor can write informatio
g g g g g g g g g
n into and retrieve information from.
g g g g g
Read only memory (ROM) - ANSWER The microprocessor can read
g g g g g g g g g
information from the ROM chip but it cannot write information into this chip.
g g g g g g g g g g g g
,Reflashing - g
gANSWER A term used to describe the reprogramming of a PCM, usually to corr
g g g g g g g g g g g g g
ect a problem repaired by updated software.
g g g g g g
Short-term fuel trim (short-term FT) -g g g g g
gANSWER adds or subtracts fuel to correct for small or temporary changes.
g g g g g g g g g g g
Snapshot - g
gANSWER A feature of OBD II systems that captures all data present whe
g g g g g g g g g g g g
n the computer detects a problem and sets a trouble code.
g g g g g g g g g g
Trip - g
gANSWER Starting and driving the vehicle until five monitors are comple
g g g g g g g g g g
ted.
Type A misfire - g g g
gANSWER A misfire that can cause immediate catalyst damage.
g g g g g g g g
Type B misfire - g g g
gANSWER A misfire that results in one and one half times the emission output sta
g g g g g g g g g g g g g g
ndard.
computer-controlled engine systems that help provide more power, better g g g g g g g g
performance, lower emissions, and better fuel economy. - ANSWER
g g g g g g g g
The On-Board Diagnostic II (OBD II) systems were developed in response to
g g g g g g g g g g g
the federal government's and the state of California's emission control system
g g g g g g g g g g
monitoring standards for all automotive manufacturers. - ANSWER
g g g g g g g
The main goal of OBD II was to detect when engine or system wear or when com
g g g g g g g g g g g g g g g g
ponent failure caused exhaust emissions to increase by 50 percent or more -
g g g g g g g g g g g g
ANSWER
g
System Functions - ANSWER g g g
All systems require multiple input signals to indicate
g g , g g g g g g
, and engine g g g
used to determine fuel and spark requirements. The v g g g g g g g g
ehicle's computer is programmed to execute specific commands based on the in
g g g g g g g g g g g
put data. - ANSWER engine load, speed, temperatures
g g g g g g g
, For example, the computer commands control fuel injectors, spark ignition timin
g g g g g g g g g g
g, emission devices, and actuators or other system components to obtain optimal
g g g g g g g g g g g g
performance and emissions. - ANSWER g g g g
The first of the design features of computerized engine management is to maintai
g g g g g g g g g g g g
n air-fuel ratios as close to
g g g g g g
to allow optimal catalytic converter operation a g g g g g g
nd improve g . - ANSWER 14.7:1, fuel economy.
g g g g g g
The second of the design features of computerized engine management is to A
g g g g g g g g g g g g
ccurately control critical g g g
devices such as EGR and carbon ca g g g g g g
nister/evaporative control system. - ANSWER emission control g g g g g g
The third of the design features of computerized engine management is to P
g g g g g g g g g g g g
recisely control g under all driving conditions adjusted for
g g g g g g
. - ANSWER ignition timing, climate and fuel grade.
g g g g g g g g
The fourth of the design features of computerized engine management is to Provi
g g g g g g g g g g g g
de more efficient cold engine operation with
g g and g .- g g g g g
ANSWER lower emissions, faster warm-ups.
g g g g g
Computer Operation - ANSWER g g g
A computer is an electronic device that
g g g g g g g
data. It is also capable of g g g g g g
operating other computers. The operation of a computer is divided into four basi
g g g g g g g g g g g g
c functions: - ANSWER stores and processes,
g g g g g g
Input. A g sent from an input device. The device can be a
g g g g g g g g g g
activated by the driver, technician, or mechanical part. - g g g g g g g g
gANSWER voltage signal, sensor or buttong g g g g
Processing. The computer uses the input information and compares it to progra
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mmed g . This information is processed by g g g g g g
in the computer. - g g g
gANSWER instructions, logic circuits g g g
Storage. The program instructions are stored in the computer's
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. Some of the input g g g g
signals are also stored in memory for
g g g g later. - g g g g g
gANSWER memory, processing g g
g g g g g g g
AND COMPUTER SYSTEMS EXAM QUESTIONS AND
g g g g g g
ANSWERS
Adaptive strategy - g g
ANSWER The ability of a computer to adapt to certain defects in the system.
g g g g g g g g g g g g g g
Calibration - ANSWER A set of instructions programmed into the PCM or
g g g g g g g g g g g
contained on a PROM that tailors the PCM to the vehicle.
g g g g g g g g g g
Catalyst efficiency monitor -
g g g
gANSWER A monitor in OBD II systems that checks the oxygen content of the e
g g g g g g g g g g g g g g
xhaust before it enters the catalytic converter and after it leaves the converter.
g g g g g g g g g g g g
Comprehensive component monitor (CCM) - g g g g
gANSWER One of the monitor systems in an OBD II system that checks the act
g g g g g g g g g g g g g g
ivity and efficiency of several systems and major components.
g g g g g g g g
Cylinder misfire monitoring - g g g
ANSWER crankshaft speed acceleration as each cylinder fires.
g g g g g g g g
Drive cycle - ANSWER A specified set of driving conditions. The drive cycle
g g g g g g g g g g g g
is important to adaptive strategies of a computer. The proper drive cycle is also
g g g g g g g g g g g g g
required of OBD II systems to complete monitor tests on certain systems.
g g g g g g g g g g g
Electronically erasable programmable read only memory (EEPROM) -g g g g g g g
ANSWER A computer chip that may be easily erased and reprogrammed with s
g g g g g g g g g g g g g
pecial equipment.
g
Enable criteria - g g
gANSWER Conditions that must be met before the PCM can initiate a test of a co
g g g g g g g g g g g g g g g
mponent or system. These criteria are specific to the sensor or system being teste
g g g g g g g g g g g g g
d.
Failure record - ANSWER Some manufacturers such as GM have provided
g g g g g g g g g g
more than one freeze frame known as "failure records." See freeze frame.
g g g g g g g g g g g
,Flashing - g
gANSWER A term that is used to describe programming an OBD II PCM.
g g g g g g g g g g g g
Fuel system monitor - ANSWER A monitor that checks short- and long-
g g g g g g g g g g g
term fuel corrections during closed loop.
g g g g g
Heated oxygen sensor - g g g
gANSWER A sensor that is electrically heated to accurately sense exhaust
g g g g g g g g g g g
gases regardless of operating temperature.
g g g g
Information retrieval - g g
gANSWER Refers to the microprocessor retrieving information from some
g g g g g g g g g
of the computer memories.
g g g
Information storage - ANSWER Refers to the microprocessor sending
g g g g g g g g
information to some of the memories where it is stored for future reference.
g g g g g g g g g g g g
Keep alive memory (KAM) -
g g g g
gANSWER The microprocessor can read information from the KAM but it cann
g g g g g g g g g g g
ot write information into this chip. KAM memory is retained when the ignition s
g g g g g g g g g g g g g
witch is turned off, but it is erased when battery power is disconnected from the c
g g g g g g g g g g g g g g g
omputer.
Long-term fuel trim (long-term FT) - ANSWER Moves slowly to keep short-
g g g g g g g g g g g
term fuel trim near zero.
g g g g g
Microprocessor - ANSWER The decision-making chip in a computer. g g g g g g g g
Parameter identification (PID) - g g g
gANSWER A mode that allows access to certain data. g g g g g g g g
Programmable read only memory (PROM) - g g g g g
gANSWER A computer chip containing some of the computer program. This
g g g g g g g g g g
chip is removeable in some computers.
g g g g g g
Random access memory (RAM) - g g g g
gANSWER A computer chip that the microprocessor can write informatio
g g g g g g g g g
n into and retrieve information from.
g g g g g
Read only memory (ROM) - ANSWER The microprocessor can read
g g g g g g g g g
information from the ROM chip but it cannot write information into this chip.
g g g g g g g g g g g g
,Reflashing - g
gANSWER A term used to describe the reprogramming of a PCM, usually to corr
g g g g g g g g g g g g g
ect a problem repaired by updated software.
g g g g g g
Short-term fuel trim (short-term FT) -g g g g g
gANSWER adds or subtracts fuel to correct for small or temporary changes.
g g g g g g g g g g g
Snapshot - g
gANSWER A feature of OBD II systems that captures all data present whe
g g g g g g g g g g g g
n the computer detects a problem and sets a trouble code.
g g g g g g g g g g
Trip - g
gANSWER Starting and driving the vehicle until five monitors are comple
g g g g g g g g g g
ted.
Type A misfire - g g g
gANSWER A misfire that can cause immediate catalyst damage.
g g g g g g g g
Type B misfire - g g g
gANSWER A misfire that results in one and one half times the emission output sta
g g g g g g g g g g g g g g
ndard.
computer-controlled engine systems that help provide more power, better g g g g g g g g
performance, lower emissions, and better fuel economy. - ANSWER
g g g g g g g g
The On-Board Diagnostic II (OBD II) systems were developed in response to
g g g g g g g g g g g
the federal government's and the state of California's emission control system
g g g g g g g g g g
monitoring standards for all automotive manufacturers. - ANSWER
g g g g g g g
The main goal of OBD II was to detect when engine or system wear or when com
g g g g g g g g g g g g g g g g
ponent failure caused exhaust emissions to increase by 50 percent or more -
g g g g g g g g g g g g
ANSWER
g
System Functions - ANSWER g g g
All systems require multiple input signals to indicate
g g , g g g g g g
, and engine g g g
used to determine fuel and spark requirements. The v g g g g g g g g
ehicle's computer is programmed to execute specific commands based on the in
g g g g g g g g g g g
put data. - ANSWER engine load, speed, temperatures
g g g g g g g
, For example, the computer commands control fuel injectors, spark ignition timin
g g g g g g g g g g
g, emission devices, and actuators or other system components to obtain optimal
g g g g g g g g g g g g
performance and emissions. - ANSWER g g g g
The first of the design features of computerized engine management is to maintai
g g g g g g g g g g g g
n air-fuel ratios as close to
g g g g g g
to allow optimal catalytic converter operation a g g g g g g
nd improve g . - ANSWER 14.7:1, fuel economy.
g g g g g g
The second of the design features of computerized engine management is to A
g g g g g g g g g g g g
ccurately control critical g g g
devices such as EGR and carbon ca g g g g g g
nister/evaporative control system. - ANSWER emission control g g g g g g
The third of the design features of computerized engine management is to P
g g g g g g g g g g g g
recisely control g under all driving conditions adjusted for
g g g g g g
. - ANSWER ignition timing, climate and fuel grade.
g g g g g g g g
The fourth of the design features of computerized engine management is to Provi
g g g g g g g g g g g g
de more efficient cold engine operation with
g g and g .- g g g g g
ANSWER lower emissions, faster warm-ups.
g g g g g
Computer Operation - ANSWER g g g
A computer is an electronic device that
g g g g g g g
data. It is also capable of g g g g g g
operating other computers. The operation of a computer is divided into four basi
g g g g g g g g g g g g
c functions: - ANSWER stores and processes,
g g g g g g
Input. A g sent from an input device. The device can be a
g g g g g g g g g g
activated by the driver, technician, or mechanical part. - g g g g g g g g
gANSWER voltage signal, sensor or buttong g g g g
Processing. The computer uses the input information and compares it to progra
g g g g g g g g g g g
mmed g . This information is processed by g g g g g g
in the computer. - g g g
gANSWER instructions, logic circuits g g g
Storage. The program instructions are stored in the computer's
g g g g g g g g g
. Some of the input g g g g
signals are also stored in memory for
g g g g later. - g g g g g
gANSWER memory, processing g g
