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Table of Contents
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SAFETY PRECAUTIONS SAFETY FIRST! ...................................................................... 1
SCAN TOOL CONTROLS CONTROLS AND INDICATORS ............................................. 2 DISPLAY FUNCTIONS ........................................................... 4 BATTERY REPLACEMENT .................................................... 5
ONBOARD DIAGNOSTICS COMPUTER ENGINE CONTROLS ........................................ 7 DIAGNOSTIC TROUBLE CODES (DTCs) .............................. 12 OBD2 MONITORS .................................................................. 15
USING THE SCAN TOOL CODE RETRIEVAL PROCEDURE ......................................... 24 THE SYSTEM MENU .............................................................. 29 VIEWING OEM ENHANCED DTCs (except Ford/Mazda) ....... 29 VIEWING OEM ENHANCED DTCs (Ford/Mazda only) ........... 30 VIEWING ABS DTCs .............................................................. 32 VIEWING SRS DTCs .............................................................. 33 VIEWING TPMS DTCs ........................................................... 34 NETWORK TEST ................................................................... 36 ERASING DIAGNOSTIC TROUBLE CODES (DTCs) ............. 38 ABOUT REPAIRSOLUTIONS 2 ........................................... 39 CONNECTING TO BLUETOOTH / WIFI ................................. 40
LIVE DATA MODE VIEWING LIVE DATA ............................................................. 42 CUSTOMIZING LIVE DATA (PIDs) ......................................... 43 RECORDING (CAPTURING) LIVE DATA ................................ 44 LIVE DATA PLAYBACK .......................................................... 47
ADDITIONAL TESTS THE MAIN MENU .................................................................... 49 SYSTEM/ACTUATOR TESTS ................................................ 50 PERFORMING SERVICE RESETS ........................................ 96 PERFORMING A SERVICE CHECK ...................................... 104 HYBRID BATTERY CHECK, BATTERY ALTERNATOR TEST 104 SYSTEM TEST MENU ............................................................ 105 BATTERY/ALTERNATOR MONITOR ..................................... 108 VIEWING DRIVE CYCLE PROCEDURES .............................. 111 USING THE DLC LOCATOR ................................................... 112 VIEWING VEHICLE INFORMATION ...................................... 112 VIEWING THE FIRMWARE VERSION ................................... 114 THE TOOL LIBRARY .............................................................. 114 TOOL SETTINGS ................................................................... 118
USING SCAN TOOL MEMORY VIEWING DATA IN MEMORY ................................................ 120
WARRANTY AND SERVICING LIMITED ONE YEAR WARRANTY .......................................... 121 SERVICE PROCEDURES ...................................................... 121
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Safety Precautions SAFETY FIRST!
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SAFETY FIRST! This manual describes common test procedures used by experienced service technicians. Many test procedures require precautions to avoid accidents that can result in personal injury, and/or damage to your vehicle or test equipment. Always read your vehicle's service manual and follow its safety precautions before and during any test or service procedure. ALWAYS observe the following general safety precautions:
When an engine is running, it produces carbon monoxide, a toxic and poisonous gas. To prevent serious injury or death from carbon monoxide poisoning, operate the vehicle ONLY in a well-ventilated area.
To protect your eyes from propelled objects as well as hot or caustic liquids, always wear approved safety eye protection.
When an engine is running, many parts (such as the coolant fan, pulleys, fan belt etc.) turn at high speed. To avoid serious injury, always be aware of moving parts. Keep a safe distance from these parts as well as other potentially moving objects.
Engine parts become very hot when the engine is running. To prevent severe burns, avoid contact with hot engine parts.
Before starting an engine for testing or troubleshooting, make sure the parking brake is engaged. Put the transmission in park (for automatic transmission) or neutral (for manual transmission). Block the drive wheels with suitable blocks. Connecting or disconnecting test equipment when the ignition is ON can damage test equipment and the vehicle's electronic components. Turn the ignition OFF before connecting the Scan Tool to or disconnecting the Scan Tool from the vehicles Data Link Connector (DLC).
To prevent damage to the on-board computer when taking vehicle electrical measurements, always use a digital multimeter with at least 10 megOhms of impedance.
Fuel and battery vapors are highly flammable. To prevent an explosion, keep all sparks, heated items and open flames away from the battery and fuel / fuel vapors. DO NOT SMOKE NEAR THE VEHICLE DURING TESTING.
Don't wear loose clothing or jewelry when working on an engine. Loose clothing can become caught in the fan, pulleys, belts, etc. Jewelry is highly conductive, and can cause a severe burn if it makes contact between a power source and ground.
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Scan Tool Controls CONTROLS AND INDICATORS
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CONTROLS AND INDICATORS
Figure 1. Controls and Indicators See Figure 1 for the locations of items 1 through 22, below.
1. ERASE button - Erases Diagnostic Trouble Codes (DTCs), and Freeze Frame data from the vehicles computer, and resets Monitor status.
2. SYSTEM MENU button When pressed, displays the System Menu.
3. DTC/FF button - Displays the DTC View screen and/or scrolls the LCD display to view DTCs and Freeze Frame data.
4. POWER/LINK button - When not connected to a vehicle, turns the Scan Tool On and Off (press and hold for 3 seconds). When connected to a vehicle, links the Scan Tool to the vehicles PCM.
5. M button When pressed, displays the Main Menu.
6. LD button When pressed while linked to a vehicle, places the Scan Tool in Live Data mode.
7. UP button When in MENU mode, scrolls UP through the menu options. When LINKED to a vehicle, scrolls UP through the current display screen to display additional data.
8. ENTER button - When in MENU mode, confirms the selected option or value.
9. DOWN button - When in MENU mode, scrolls DOWN through the menu options. When LINKED to a vehicle, scrolls DOWN through the current display screen to display additional data.
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Scan Tool Controls CONTROLS AND INDICATORS
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10. Left Soft Key - selects the associated option shown on the display (Yes/No, Previous/Next, etc).
11. Right Soft Key - selects the associated option shown on the display (Yes/No, Previous/Next, etc).
12. GREEN LED - Indicates that all engine systems are running normally (all Monitors on the vehicle are active and performing their diagnostic testing, and no DTCs are present).
13. YELLOW LED - Indicates there is a possible problem. A Pending DTC is present and/or some of the vehicles emission monitors have not run their diagnostic testing.
14. RED LED - Indicates there is a problem in one or more of the vehicles systems. The red LED is also used to show that DTC(s) are present. DTCs are shown on the Scan Tools display. In this case, the Malfunction Indicator (Check Engine) lamp on the vehicles instrument panel will light steady on.
15. Display - Color LCD display shows menus and submenus, test results, Scan Tool functions and Monitor status information. See DISPLAY FUNCTIONS, following, for more details.
16. CABLE - Connects the Scan Tool to the vehicles Data Link Connector (DLC).
Items 17 through 22 are available with purchase of the optional OBD1 Adaptor Kit and OBD1 firmware upgrade.
17. CHRYSLER Connector Cable Adaptor - Installs on cable (item 14) when connecting to a Chrysler OBD1 Data Link Connector.
18. FORD Connector Cable Adaptor - Installs on cable (item 14) when connecting to a Ford OBD1 Data Link Connector.
19. GM Connector Cable Adaptor - Installs on cable (item 14) when connecting to a GM OBD1 Data Link Connector.
20. HONDA Connector Cable Adaptor - Installs on cable (item 14) when connecting to a Honda OBD1 Data Link Connector.
21. OBD II Cable - Connects the scan tool to the vehicle's Data Link Connector (DLC) when retrieving codes from OBD II systems.
22. TOYOTA Connector Cable Adaptor - Installs on cable (item 14) when connecting to a Toyota OBD1 Data Link Connector.
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Scan Tool Controls DISPLAY FUNCTIONS
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DISPLAY FUNCTIONS
Figure 2. Display Functions See Figure 2 for the locations of items 1 through 15, below. 1. I/M MONITOR STATUS field - Identifies the I/M Monitor status area. 2. Monitor icons - Indicate which Monitors are supported by the
vehicle under test, and whether or not the associated Monitor has run its diagnostic testing (Monitor status). A solid green icon indicates the associated Monitor has completed its diagnostic testing. A flashing red icon indicates that the vehicle supports the associated Monitor, but the Monitor has not yet run its diagnostic testing.
3. Vehicle icon When visible, indicates that the Scan Tool is being powered through the vehicles DLC connector.
4. Link icon - When visible, indicates the Scan Tool is communicating with the vehicles computer.
5. Computer icon - When t visible, indicates the Scan Tool is linked to a personal computer.
6. Scan Tool Internal Battery icon - When visible, indicates the Scan Tool batteries are low and should be replaced. If the batteries are not replaced when the battery symbol is "on", all 3 LEDs will light to warn that the batteries need replacement. No data is displayed on screen when all 3 LEDs are lit.
7. DTC Display Area - Displays the Diagnostic Trouble Code (DTC) number. Each fault is assigned a code number that is specific to that fault. The DTC number is color-coded as follows: RED - Indicates the currently displayed DTC is a STORED or
PERMANENT DTC. YELLOW - Indicates the currently displayed DTC is a PENDING
DTC.
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Scan Tool Controls BATTERY REPLACEMENT
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GREEN - In cases where no codes are retrieved, a No DTCs are presently stored in the vehicles computer message is shown in green.
8. Code Number Sequence - The Scan Tool assigns a sequence number to each DTC that is present in the computers memory, starting with 1. This number indicates which code is currently displayed. Code number 1 is always the highest priority code, and the one for which Freeze Frame data has been stored.
If 1 is a Pending code, there may or may not be Freeze Frame data stored in memory.
9. Code Enumerator - Indicates the total number of codes retrieved from the vehicles computer.
10. Test Data Display Area - Displays DTC definitions, Freeze Frame data and other pertinent test information messages.
11. SYSTEM icon - Indicates the system with which the code is associated:
MIL icon ABS icon SRS icon
12. FREEZE FRAME icon - Indicates that there is Freeze Frame data from Priority Code (Code #1) stored in the vehicles computer memory.
13. Code type - Indicates the type of code being displayed; Generic Stored, Generic Pending, Generic permanent, etc.
14. Severity - Indicates the level of severity for the priority code (code number 1), as follows: 1 -Service should be scheduled and repairs made when
convenient. This DTC typically has no immediate threat to essential system components in the short term.
2 -Repair immediately if drivability issues are present. Threat to essential system components if not repaired as soon as possible.
3 -Stop and repair vehicle immediately to prevent interrelated failures. Harmful and damaging to essential system components.
15. Bluetooth icon Indicates communication status with a compat- ible Innova mobile application A solid blue icon indicates an active Bluetooth connection has been established.
16. Wi-Fi icon Indicates Wi-Fi communication status. When ON, indicates the scan tool is linked to a Wi-Fi network. When OFF, indicates there is no Wi-Fi connection.
BATTERY REPLACEMENT
Replace batteries when the battery symbol is visible on display and/or the 3 LEDS are all lit and no other data is visible on screen. 1. Locate the battery cover on the back of the Scan Tool. 2. Slide the battery cover off (use your fingers).
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Scan Tool Controls BATTERY REPLACEMENT
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3. Replace batteries with three AA-size batteries (for longer life, use Alkaline-type batteries).
4. Reinstall the battery cover on the back of the Scan Tool.
Adjustments After Battery Installation The first time the Scan Tool is turned on, you must select the desired display language (English, French or Spanish) and unit of measurement (Standard or metric) as follows: 1. Press and hold POWER/LINK to turn the Scan Tool ON.
The Select Language screen displays.
2. Select the desired display language, then press ENTER . The Select Unit screen displays.
3. Select the desired unit of measurement, then press ENTER . The Firmware Version screen displays.
After the initial language and unit of measurement selections are performed, these, as well as other settings, can be changed as desired. Proceed to TOOL SETTINGS on page 118 for further instructions.
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Onboard Diagnostics COMPUTER ENGINE CONTROLS
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COMPUTER ENGINE CONTROLS
The Introduction of Electronic Engine Controls
As a result of increased air pollution (smog) in large cities, such as Los Angeles, the California Air Resources Board (CARB) and the Environmental Protection Agency (EPA) set new regulations and air pollution standards to deal with the problem. To further complicate matters, the energy crisis of the early 1970s caused a sharp increase in fuel prices over a short period. As a result, vehicle manufacturers were not only required to comply with the new emissions standards, they also had to make their vehicles more fuel-efficient. Most vehicles were required to meet a miles-per-gallon (MPG) standard set by the U.S. Federal Government. Precise fuel delivery and spark timing are needed to reduce vehicle emissions. Mechanical engine controls in use at the time (such as ignition points, mechanical spark advance and the carburetor) responded too slowly to driving conditions to properly control fuel delivery and spark timing. This made it difficult for vehicle manufacturers to meet the new standards. A new Engine Control System had to be designed and integrated with the engine controls to meet the stricter standards. The new system had to: Respond instantly to supply the proper mixture of air and fuel for any
driving condition (idle, cruising, low-speed driving, high-speed driving, etc.).
Calculate instantly the best time to ignite the air/fuel mixture for maximum engine efficiency.
Perform both these tasks without affecting vehicle performance or fuel economy.
Vehicle Computer Control Systems can perform millions of calculations each second. This makes them an ideal substitute for the slower mechanical engine controls. By switching from mechanical to electronic engine controls, vehicle manufacturers are able to control fuel delivery and spark timing more precisely. Some newer Computer Control Systems also provide control over other vehicle functions, such as transmission, brakes, charging, body, and suspension systems.
Electronic Computer Control Systems make it possible for vehicle manufacturers to comply with the tougher emissions and fuel efficiency standards mandated by
State and Federal Governments.
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Onboard Diagnostics COMPUTER ENGINE CONTROLS
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The Basic Engine Computer Control System
The on-board computer is the heart of the Computer Control System. The computer contains several programs with preset reference values for air/fuel ratio, spark or ignition timing, injector pulse width, engine speed, etc. Separate values are provided for various driving conditions, such as idle, low speed driving, high-speed driving, low load, or high load. The preset reference values represent the ideal air/fuel mixture, spark timing, transmission gear selection, etc., for any driving condition. These values are programmed by the vehicle manufacturer, and are specific to each vehicle model. Most on-board computers are located inside the vehicle behind the dashboard, under the passengers or drivers seat, or behind the right kick panel. However, some manufacturers may still position it in the engine compartment. Vehicle sensors, switches, and actuators are located throughout the engine, and are connected by electrical wiring to the on-board computer. These devices include oxygen sensors, coolant temperature sensors, throttle position sensors, fuel injectors, etc. Sensors and switches are input devices. They provide signals representing current engine operating conditions to the computer. Actuators are output devices. They perform actions in response to commands received from the computer. The on-board computer receives information inputs from sensors and switches located throughout the engine. These devices monitor critical engine conditions such as coolant temperature, engine speed, engine load, throttle position, air/fuel ratio etc. The computer compares the values received from these sensors with its preset reference values, and makes corrective actions as needed so that the sensor values always match the preset reference values for the current driving condition. The computer makes adjustments by commanding other devices such as the fuel injectors, idle air control, EGR valve or Ignition Module to perform these actions.
The Computer Control System consists of an on-board computer and several related control devices (sensors,
switches, and actuators).
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Onboard Diagnostics COMPUTER ENGINE CONTROLS
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Vehicle operating conditions are constantly changing. The computer continuously makes adjustments or corrections (especially to the air/fuel mixture and spark timing) to keep all the engine systems operating within the preset reference values.
On-Board Diagnostics - First Generation (OBD1)
Beginning in 1988, Californias Air Resources Board (CARB), and later the Environmental Protection Agency (EPA)
required vehicle manufacturers to include a self-diagnostic program in their on-board computers. The program would be
capable of identifying emissions-related faults in a system. The first generation of Onboard Diagnostics came to be known as OBD1. OBD1 is a set of self-testing and diagnostic instructions programmed into the vehicles on-board computer. The
programs are specifically designed to detect failures in the sensors, actuators, switches and wiring of the various vehicle emissions-related systems. If the computer detects a failure in any of these components or systems, it lights an indicator on the dashboard to alert the driver. The indicator lights only when an emissions-related problem is detected. The computer also assigns a numeric code for each specific problem that it detects, and stores these codes in its memory for later retrieval. These codes can be retrieved from the computers memory with the use of a Code Reader or a Scan Tool.
On-Board Diagnostics - Second Generation (OBD2)
In addition to performing all the functions of the OBD1 System, the OBD2 System has been enhanced with new Diagnostic Programs. These programs closely monitor the functions of various emissions-related compo- nents and systems (as well as other systems) and make this information readily available (with the proper equipment) to the technician for evaluation. The California Air Resources Board (CARB) conducted studies on OBD1 equipped vehicles. The information that was gathered from these studies showed the following: A large number of vehicles had deteriorating or degraded
emissions-related components. These components were causing an increase in emissions.
With the exception of some 1994 and 1995 vehicles, most vehicles from 1982 to 1995 are equipped with
some type of first generation On-Board Diagnostics.
The OBD2 System is an enhancement of the
OBD1 System.
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Because OBD1 systems only detect failed components, the degraded components were not setting codes.
Some emissions problems related to degraded components only occur when the vehicle is being driven under a load. The emission checks being conducted at the time were not performed under simulated driving conditions. As a result, a significant number of vehicles with degraded components were passing Emissions Tests.
Codes, code definitions, diagnostic connectors, communication protocols and emissions terminology were different for each manufacturer. This caused confusion for the technicians working on different make and model vehicles.
To address the problems made evident by this study, CARB and the EPA passed new laws and standardization requirements. These laws required that vehicle manufacturers to equip their new vehicles with devices capable of meeting all of the new emissions standards and regulations. It was also decided that an enhanced on-board diagnostic system, capable of addressing all of these problems, was needed. This new system is known as On-Board Diagnostics Generation Two (OBD2). The primary objective of the OBD2 system is to comply with the latest regulations and emissions standards established by CARB and the EPA. The Main Objectives of the OBD2 System are: To detect degraded and/or failed emissions-related components or
systems that could cause tailpipe emissions to exceed by 1.5 times the Federal Test Procedure (FTP) standard.
To expand emissions-related system monitoring. This includes a set of computer run diagnostics called Monitors. Monitors perform diagnostics and testing to verify that all emissions-related components and/or systems are operating correctly and within the manufacturers specifications.
To use a standardized Diagnostic Link Connector (DLC) in all vehicles. (Before OBD2, DLCs were of different shapes and sizes.)
To standardize the code numbers, code definitions and language used to describe faults. (Before OBD2, each vehicle manufacturer used their own code numbers, code definitions and language to describe the same faults.)
To expand the operation of the Malfunction Indicator Lamp (MIL). To standardize communication procedures and protocols between
the diagnostic equipment (Scan Tools, Code Readers, etc.) and the vehicles on-board computer.
OBD2 Terminology
The following terms and their definitions are related to OBD2 systems. Read and reference this list as needed to aid in the understanding of OBD2 systems.
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Onboard Diagnostics COMPUTER ENGINE CONTROLS
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Powertrain Control Module (PCM) - The PCM is the OBD2 accepted term for the vehicles on-board computer. In addition to controlling the engine management and emissions systems, the PCM also participates in controlling the powertrain (transmission) operation. Most PCMs also have the ability to communicate with other computers on the vehicle (ABS, ride control, body, etc.).
Monitor - Monitors are diagnostic routines programmed into the PCM. The PCM utilizes these programs to run diagnostic tests, and to monitor operation of the vehicles emissions-related components or systems to ensure they are operating correctly and within the vehicles manufacturer specifications. Currently, up to fifteen Monitors are used in OBD2 systems. Additional Monitors will be added as the OBD2 system is further developed.
Not all vehicles support all fifteen Monitors.
Enabling Criteria - Each Monitor is designed to test and monitor the operation of a specific part of the vehicles emissions system (EGR system, oxygen sensor, catalytic converter, etc.). A specific set of conditions or driving procedures must be met before the computer can command a Monitor to run tests on its related system. These conditions are known as Enabling Criteria. The requirements and procedures vary for each Monitor. Some Monitors only require the ignition key to be turned On for them to run and complete their diagnostic testing. Others may require a set of complex procedures, such as, starting the vehicle when cold, bringing it to operating temperature, and driving the vehicle under specific conditions before the Monitor can run and complete its diagnostic testing.
Monitor Has/Has Not Run - The terms Monitor has run or Monitor has not run are used throughout this manual. Monitor has run, means the PCM has commanded a particular Monitor to perform the required diagnostic testing on a system to ensure the system is operating correctly (within factory specifications). The term Monitor has not run means the PCM has not yet commanded a particular Monitor to perform diagnostic testing on its associated part of the emissions system.
Trip - A Trip for a particular Monitor requires that the vehicle is being driven in such a way that all the required Enabling Criteria for the Monitor to run and complete its diagnostic testing are met. The Trip Drive Cycle for a particular Monitor begins when the ignition key is turned On. It is successfully completed when all the Enabling Criteria for the Monitor to run and complete its diagnostic testing are met by the time the ignition key is turned Off. Since each of the fifteen monitors is designed to run diagnostics and testing on a different part of the engine or emissions system, the Trip Drive Cycle needed for each individual Monitor to run and complete varies.
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Onboard Diagnostics DIAGNOSTIC TROUBLE CODES (DTCs)
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OBD2 Drive Cycle - An OBD2 Drive Cycle is an extended set of driving procedures that takes into consideration the various types of driving conditions encountered in real life. These conditions may include starting the vehicle when it is cold, driving the vehicle at a steady speed (cruising), accelerating, etc. An OBD2 Drive Cycle begins when the ignition key is turned On (when cold) and ends when the vehicle has been driven in such a way as to have all the Enabling Criteria met for all its applicable Monitors. Only those trips that provide the Enabling Criteria for all Monitors applicable to the vehicle to run and complete their individual diagnostic tests qualify as an OBD2 Drive Cycle. OBD2 Drive Cycle requirements vary from one model of vehicle to another. Vehicle manufacturers set these procedures. Consult your vehicles service manual for OBD2 Drive Cycle procedures.
Do not confuse a Trip Drive Cycle with an OBD2 Drive Cycle. A Trip Drive Cycle provides the Enabling Criteria for one specific Monitor to run and complete its diagnostic testing. An OBD2 Drive Cycle must meet the Enabling Criteria for all Monitors on a particular vehicle to run and complete their diagnostic testing.
Warm-up Cycle - Vehicle operation after an engine off period where engine temperature rises at least 40F (22C) from its temperature before starting, and reaches at least 160F (70C). The PCM uses warm-up cycles as a counter to automatically erase a specific code and related data from its memory. When no faults related to the original problem are detected within a specified number of warm-up cycles, the code is erased automatically.
DIAGNOSTIC TROUBLE CODES (DTCs) Diagnostic Trouble Codes (DTCs) are meant to guide you to the proper service procedure in the vehicles service manual. DO NOT replace parts based only on DTCs without first consulting the vehicles service manual for proper testing procedures for that particular system, circuit or component. DTCs are alphanumeric codes that are used to identify a problem that is present in any of the systems that are monitored by the on-board computer (PCM). Each trouble code has an assigned message that identifies the circuit, component or system area where the problem was found. OBD2 diagnostic trouble codes are made up of five characters: The 1st character is a letter (B, C, P or U). It identifies the
main system where the fault occurred (Body, Chassis, Powertrain, or Network).
The 2nd character is a numeric digit (0 thru 3). It identifies the type of code (Generic or Manufacturer-Specific).
Generic DTCs are codes that are used by all vehicle manu- facturers. The standards for generic DTCs, as well as their definitions, are set by the Society of Automotive Engineers (SAE).
Diagnostic Trouble Codes (DTCs) are
codes that identify a specific problem area.
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Onboard Diagnostics DIAGNOSTIC TROUBLE CODES (DTCs)
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Manufacturer-Specific DTCs are codes that are controlled by the vehicle manufacturers. The Federal Government does not require vehicle manufacturers to go beyond the standardized generic DTCs in order to comply with the new OBD2 emissions standards. However, manufacturers are free to expand beyond the standardized codes to make their systems easier to diagnose.
The 3rd character is a letter or a numeric digit (0 thru 9, A thru F). It identifies the specific system or sub-system where the problem is located.
The 4th and 5th characters are letters or numeric digits (0 thru 9, A thru F). They identify the section of the system that is malfunctioning.
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Onboard Diagnostics DIAGNOSTIC TROUBLE CODES (DTCs)
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DTCs and MIL Status When the vehicles on-board computer detects a failure in an emissions-related component or system, the computers internal diagnostic program assigns a diagnostic trouble code (DTC) that points to the system (and subsystem) where the fault was found. The diagnostic program saves the code in the computers memory. It records a Freeze Frame of conditions present when the fault was found, and lights the Malfunction Indicator Lamp (MIL). Some faults require detection for two trips in a row before the MIL is turned on.
The Malfunction Indicator Lamp (MIL) is the accepted term used to describe the lamp on the dashboard that lights to warn the driver that an emissions-related fault has been found. Some manufacturers may still call this lamp a Check Engine or Service Engine Soon light.
There are two types of DTCs used for emissions-related faults: Type A and Type B. Type A codes are One-Trip codes; Type B DTCs are usually Two-Trip DTCs. When a Type A DTC is found on the First Trip, the following events take place: The computer commands the MIL On when the failure is first found. If the failure causes a severe misfire that may cause damage to the
catalytic converter, the MIL flashes once per second. The MIL continues to flash as long as the condition exists. If the condition that caused the MIL to flash is no longer present, the MIL will light steady On.
A DTC is saved in the computers memory for later retrieval. A Freeze Frame of the conditions present in the engine or emissions
system when the MIL was ordered On is saved in the computers memory for later retrieval. This information shows fuel system status (closed loop or open loop), engine load, coolant temperature, fuel trim value, MAP vacuum, engine RPM and DTC priority.
When a Type B DTC is found on the First Trip, the following events take place: The computer sets a Pending DTC, but the MIL is not ordered On.
Freeze Frame data may or may not be saved at this time depending on manufacturer. The Pending DTC is saved in the computers memory for later retrieval.
If the failure is found on the second consecutive trip, the MIL is ordered On. Freeze Frame data is saved in the computers memory.
If the failure is not found on the second Trip, the Pending DTC is erased from the computers memory.
The MIL will stay lit for both Type A and Type B codes until one of the following conditions occurs:
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Onboard Diagnostics OBD2 MONITORS
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If the conditions that caused the MIL to light are no longer present for the next three trips in a row, the computer automatically turns the MIL Off if no other emissions-related faults are present. However, the DTCs remain in the computers memory as a history code for 40 warm-up cycles (80 warm-up cycles for fuel and misfire faults). The DTCs are automatically erased if the fault that caused them to be set is not detected again during that period.
Misfire and fuel system faults require three trips with similar conditions before the MIL is turned Off. These are trips where the engine load, RPM and temperature are similar to the conditions present when the fault was first found.
After the MIL has been turned off, DTCs and Freeze Frame data stay in the computers memory.
Erasing the DTCs from the computers memory can also turn off the MIL. See ERASING DIAGNOSTIC TROUBLE CODES (DTCs) on page 38, before erasing codes from the computers memory. If a Diagnostic Tool or Scan Tool is used to erase the codes, Freeze Frame data will also be erased.
OBD2 MONITORS To ensure the correct operation of the various emissions-related components and systems, a diagnostic program was developed and installed in the vehicles on-board computer. The program has several procedures and diagnostic strategies. Each procedure or diagnostic strategy is made to monitor the operation of, and run diagnostic tests on, a specific emissions-related component or system. These tests ensure the system is running correctly and is within the manufacturers specifications. On OBD2 systems, these procedures and diagnostic strategies are called Monitors. Currently, fifteen Monitors are supported by OBD2 systems. Additional monitors may be added as a result of Government regulations as the OBD2 system grows and matures. Not all vehicles support all fifteen Monitors. Additionally, some Monitors are supported by spark ignition vehicles only, while others are supported by compression ignition vehicles only. Monitor operation is either Continuous or Non-Continuous, depending on the specific monitor.
Continuous Monitors
Three of these Monitors are designed to constantly monitor their associated components and/or systems for proper operation. Continuous Monitors run constantly when the engine is running. The Continuous Monitors are:
Comprehensive Component Monitor (CCM)
Misfire Monitor
Fuel System Monitor
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Non-Continuous Monitors
The other twelve Monitors are non-continuous Monitors. Non- continuous Monitors perform and complete their testing once per trip. The non-continuous Monitors are:
Oxygen Sensor Monitor
Oxygen Sensor Heater Monitor
Catalyst Monitor
Heated Catalyst Monitor
EGR System Monitor
EVAP System Monitor
Secondary Air System Monitor The following Monitors became standard beginning in 2010. The majority of vehicles produced before this time will not support these Monitors
NMHC Monitor
NOx Adsorber Monitor
Boost Pressure System Monitor
Exhaust Gas Sensor Monitor
PM Filter Monitor
The following provides a brief explanation of the function of each Monitor:
Comprehensive Component Monitor (CCM) - This Monitor continuously checks all inputs and outputs from sensors,
actuators, switches and other devices that provide a signal to the computer. The Monitor checks for shorts, opens, out of range value, functionality and rationality.
Rationality: Each input signal is compared against all other inputs and against information in the computers memory to see if it makes sense under the current operating conditions. Example: The signal from the throttle position sensor indicates the vehicle is in a wide-open throttle condition, but the vehicle is really at idle, and the idle condition is confirmed by the signals from all other sensors. Based on the input data, the computer determines that the signal from the throttle position sensor is not rational (does not make sense when compared to the other inputs). In this case, the signal would fail the rationality test.
The CCM is supported by both spark ignition vehicles and compression ignition vehicles. The CCM may be either a One-Trip or a Two-Trip Monitor, depending on the component.
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Fuel System Monitor - This Monitor uses a Fuel System Correction program, called Fuel Trim, inside the on-board
computer. Fuel Trim is a set of positive and negative values that represent adding or subtracting fuel from the engine. This program is used to correct for a lean (too much air/not enough fuel) or rich (too much fuel/not enough air) air-fuel mixture. The program is designed to add or subtract fuel, as needed, up to a certain percent. If the correction needed is too large and exceeds the time and percent allowed by the program, a fault is indicated by the computer. The Fuel System Monitor is supported by both spark ignition vehicles and compression ignition vehicles. The Fuel System Monitor may be a One-Trip or Two-Trip Monitor, depending on the severity of the problem.
Misfire Monitor - This Monitor continuously checks for engine misfires. A misfire occurs when the air-fuel mixture in the cylinder does not
ignite. The misfire Monitor uses changes in crankshaft speed to sense an engine misfire. When a cylinder misfires, it no longer contributes to the speed of the engine, and engine speed decreases each time the affected cylinder(s) misfire. The misfire Monitor is designed to sense engine speed fluctuations and determine from which cylinder(s) the misfire is coming, as well as how bad the misfire is. There are three types of engine misfires, Types 1, 2, and 3. - Type 1 and Type 3 misfires are two-trip monitor faults. If a fault is sensed
on the first trip, the computer temporarily saves the fault in its memory as a Pending Code. The MIL is not commanded on at this time. If the fault is found again on the second trip, under similar conditions of engine speed, load and temperature, the computer commands the MIL On, and the code is saved in its long term memory.
- Type 2 misfires are the most severe type of misfire. When a Type 2 misfire is sensed on the first trip, the computer commands the MIL to light when the misfire is sensed. If the computer determines that a Type 2 misfire is severe , and may cause catalytic converter damage, it commands the MIL to flash once per second as soon as the misfire is sensed. When the misfire is no longer present, the MIL reverts to steady On condition.
The Misfire Monitor is supported by both spark ignition vehicles and compression ignition vehicles.
Catalyst Monitor - The catalytic converter is a device that is installed downstream of the exhaust manifold. It helps to oxidize
(burn) the unburned fuel (hydrocarbons) and partially burned fuel (carbon monoxide) left over from the combustion process. To accomplish this, heat and catalyst materials inside the converter react with the exhaust gases to burn the remaining fuel. Some materials inside the catalytic converter also have the ability to store oxygen, and release it as needed to oxidize hydrocarbons and carbon monoxide. In the process, it reduces vehicle emissions by converting the polluting gases into carbon dioxide and water. The computer checks the efficiency of the catalytic converter by monitoring the oxygen sensors used by the system. One sensor is located before (upstream of) the converter; the other is located after (downstream of) the converter. If the catalytic converter loses its ability to store oxygen,
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the downstream sensor signal voltage becomes almost the same as the upstream sensor signal. In this case, the monitor fails the test. The Catalyst Monitor is supported by spark ignition vehicles only. The Catalyst Monitor is a Two-Trip Monitor. If a fault is found on the first trip, the computer temporarily saves the fault in its memory as a Pending Code. The computer does not command the MIL on at this time. If the fault is sensed again on the second trip, the computer commands the MIL On and saves the code in its long-term memory.
Heated Catalyst Monitor - Operation of the heated catalytic converter is similar to the catalytic converter. The main
difference is that a heater is added to bring the catalytic converter to its operating temperature more quickly. This helps reduce emissions by reducing the converters down time when the engine is cold. The Heated Catalyst Monitor performs the same diagnostic tests as the catalyst Monitor, and also tests the catalytic converters heater for proper operation.
The Heated Catalyst Monitor is supported by spark ignition vehicles only. This Monitor is also a Two-Trip Monitor.
Exhaust Gas Recirculation (EGR) Monitor - The Exhaust Gas Recirculation (EGR) system helps reduce the formation of
Oxides of Nitrogen during combustion. Temperatures above 2500F cause nitrogen and oxygen to combine and form Oxides of Nitrogen in the combustion chamber. To reduce the formation of Oxides of Nitrogen, combustion temperatures must be kept below 2500F. The EGR system recirculates small amounts of exhaust gas back into the intake manifold, where it is mixed with the incoming air/fuel mixture. This reduces combustion temperatures by up to 500F. The computer determines when, for how long, and how much exhaust gas is recirculated back to the intake manifold. The EGR Monitor performs EGR system function tests at preset times during vehicle operation. The EGR Monitor is supported by both spark ignition vehicles and compression ignition vehicles. The EGR Monitor is a Two-Trip Monitor. If a fault is found on the first trip, the computer temporarily saves the fault in its memory as a Pending Code. The computer does not command the MIL on at this time. If the fault is sensed again on the second trip, the computer commands the MIL On, and saves the code in its long-term memory.
Evaporative System (EVAP) Monitor - OBD2 vehicles are equipped with a fuel Evaporative system (EVAP) that helps
prevent fuel vapors from evaporating into the air. The EVAP system carries fumes from the fuel tank to the engine where they are burned during combustion. The EVAP system may consist of a charcoal canister, fuel tank cap, purge solenoid, vent solenoid, flow monitor, leak detector and connecting tubes, lines and hoses. Fumes are carried from the fuel tank to the charcoal canister by hoses or tubes. The fumes are stored in the charcoal canister. The computer controls the flow of fuel vapors from the charcoal canister to the engine via a purge solenoid. The computer energizes or de-energizes the purge solenoid (depending on solenoid design). The purge solenoid opens a
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valve to allow engine vacuum to draw the fuel vapors from the canister into the engine where the vapors are burned. The EVAP Monitor checks for proper fuel vapor flow to the engine, and pressurizes the system to test for leaks. The computer runs this Monitor once per trip. The EVAP Monitor is supported by spark ignition vehicles only. The EVAP Monitor is a Two-Trip Monitor. If a fault is found on the first trip, the computer temporarily saves the fault in its memory as a Pending Code. The computer does not command the MIL on at this time. If the fault is sensed again on the second trip, the PCM commands the MIL On, and saves the code in its long-term memory.
Oxygen Sensor Heater Monitor - The Oxygen Sensor Heater Monitor tests the operation of the oxygen sensors heater. There
are two modes of operation on a computer-controlled vehicle: open- loop and closed-loop. The vehicle operates in open-loop when the engine is col
