1. OBD II UPDATE TRAINING COURSE

2. OBD II Module Outline OBD II Foundation OBD II History
OBD II Terminology
OBD I vs OBD II
OBD II MIL Operation
DTCs (A & B types
OBD II Numbering
Rationality / Normality
One/Two Trip DTCs
Freeze Frame
I/M Readiness Monitors

3. SESSION 1 OBD I FOUNDATION
Onboard Diagnostics Generation 2
Not a stand alone system
OBD II is built on top of OBD I

4. THE OBD I FOUNDATION
OBD I mandated a “Check Engine Light”
Included diagnostic trouble codes (DTCs)

5. THE OBD I FOUNDATION OBD I Mandated in 1988 Objectives
Improve emission compliance by notifying the driver that there was a malfunction
Assist in identifying malfunctioning circuits in the computer control system

6. OBD I MIL Operation Check Engine Light Operation
Illuminated when circuit was abnormal
Open, Shorted, Grounded
Illuminated intermittently when circuit operated abnormally intermittently
Didn’t always illuminate when a problem was detected!
WAS INCONSISTENT!!!

7. Serial Data Live Computer Data Supplied by the vehicle’s computer
Read via a Scan Tool
Interpreted Data
GM, Chrysler, then Ford
Now mandated by OBD II

8. Diagnosing Today’s Vehicles
Technician must have a strong foundation in system operation & theory!!!
Technician must have ability to fully utilize today’s tools
Scan Tool, DSO, 5-gas analyzer, etc.
Technician must know how theory & tools are best applied together

9. OBD I On Board Diagnostics with a Check Engine Light Mandated by CARB
Gave birth to OBD II

10. OBD II Update Training Course
Session II
OBD II Foundation

11. Session 1 The OBD I Foundation
OBD I - On Board Diagnostics with a Check Engine Light
MIL Operation Inconsistent
DTC Viewing Method Inconsistent
DTC Criteria Inconsistent
DTC Numbering Inconsistent

12. The OBD II System
The Second Generation was designed to fix the inadequacies of the First Generation
One of the biggest problems was the system must be monitored under load!

13. OBD I Mode Monitoring
Degraded emission systems did not set Check Engine Light
EVAP, CAT, & AIR were not monitored
O2S Performance not monitored
CAT killing misfires not monitored
Shifted air fuel ratios not monitored
NOx emissions not monitored (still?)

14. OBD II Strategies Implementation slated for 1996 models
Phase in to begin
OEMs allowed to EEPROM flash to lock-out problems affecting CSI
Check with manufacturer regarding current configuration

15. Setting the Standards C.A.R.B - 1994 - 1998 E.P.A. 1998 - On S.A.E.
Requirements for common systems
Programming changes

16. OBD II Requirements Must be installed on all vehicles
Must be able to determine operating condition of the vehicle’s emission control system / strategy
Diagnostics & Functions must be standardized

17. OBD II Requirements PCM must store DTCs for detected faults
DTC’s must stay in memory until cleared following repair or until 40 consecutive warm-up cycles
80 consecutive warm-up cycles if misfire and/or fuel control related

18. OBD II Requirements
The system must test emission control systems, record the results, and display those results
A MIL is mandatory
must illuminate when a fault is detected (and confirmed?)
must remain illuminated until the fault is corrected (3 tests)

19. OBD II Requirements Generic Scan Tool (GST)
SAE J 1850 and/or ISO 9141 communication protocol
Must monitor ALL OBD II information
Monitoring & DTC clearing procedures must meet CARB & EPA standards
Must display Parameter ID (PIDs)
Freeze Frame Data
PCM Parameters & Test Results

20. OBD II Requirements Monitor Test Results
Comprehensive Component Monitoring
Input Normality & Rationality
Outputs for performance or at least electrically

21. The Scan Tool (2 Tools In One?)
OBD II Generic Scan Tool (GST)
Manufacturer Specific Scan Tool
Hybrid
OBD II Generic with Manufacturer Specific Capabilities

22. OBD II Commonalties Standardization Facilitated by SAE
SAE compromised of Reps from OEMs
OBD II guidelines established by SAE
OEMs interpreted guidelines differently
OBD II is the SAME, but DIFFERENT!

23. Emission Related Monitoring
Unlike OBD I, OBD II not only monitors an actuator was commanded on, but tests the system to make sure it actually worked!!!

24. OBD II Monitors
Designed to detect failures that would cause emissions to increase by 50% or would shorten the life of the catalytic converter
The number of monitors are increasing
Monitors require more computing resources and additional sensors
Monitors are run under specific conditions

25. OBD II Program Management
Program Manager
Task Manager
Diagnostic Executive
OBD II Program Management
Artificial Intelligence
Rationality

26. OBD II Standardization
Common Diagnostic Connector
Data Link Connector (DLC)
16 pins -- 7 for SAE/OBD II & 9 for OEM
1 pin is B+ to power Scan Tool
DLC to be located on drivers side near steering column or have a location label

27. MIL Regulations
MIL will illuminate when an increase in emissions = to 1.5 X the FTP is inferred
Or when the PCM/Network itself malfunctions
The MIL shall not be used for any other purpose!!!

28. MIL Operation MIL On MIL Off MIL Flashing
a fault has been detected (and confirmed?)
MIL Off
No fault has been detected
Test have not been run
MIL Flashing
Catalyst damaging misfire or air fuel problem detected

29. Diagnostic Trouble Codes
Common numbering system for all DTCs
Alpha Numeric
5 digit
DTCs must be similar in meaning
DTC designation must be common
SAE standard J2012

30. DTC Numbering 1st Digit Alpha Character “P” - Powertrain “C” - Chassis
“B” - Body
“U” - Uart / multiplexing / networking

31. DTC Numbering 2nd Digit or thousandth position Either “1” or “0”
“0” Codes are SAE / OBD II Controlled
“1” Codes are Manufacturer Specific

32. DTC Numbering 3rd Digit or hundredth position System Fault
“100” - Fuel & Air Metering
“200” - Fuel & Air Metering (injector & fuel pump)
“300” - Misfire or Ignition System
“400” - Emission Control

33. DTC Numbering 3rd Digit or hundredth position System Fault
“500” - Vehicle Speed and/or Idle Control
“600” - Computer Output Circuits
“700” - Transmission
“800” - Transmission

34. DTC Numbering 4th & 5th Digits - tens & ones Designate Specific Fault
Example
P0301 = Engine Cylinder # 1 Misfire Detected

35. Diagnostic Trouble Codes OBD I vs. OBD II
1. OBD II requires “code enabling criteria” be met (maybe twice) before a code is stored. OBD I only needed abnormality
2. OBD II for emissions ONLY! OBD I is not. Most OEMs recommend fixing OBD I first - before checking / repairing OBD II

36. Diagnostic Trouble Codes OBD I vs. OBD II
OBD I diagnostic procedure was to…
Pull Codes
Record Codes
Erase Codes
Operate Vehicle
Erasing OBD II Codes will also erase Freeze Frame Data

37. Diagnostic Trouble Codes OBD I vs. OBD II
OBD II has no “soft codes”
OBD II diagnostic procedure
Pull Code
Record Freeze Frame Data
Repair Root Cause
Operate vehicle at Freeze Frame parameters
Meet code enable criteria
Run monitor

38. MULTIPLEXING Vehicles use multiple onboard computers
Faults in other computers can disable monitors due to multiplexing
Example
Wheel Speed Sensors used to verify rough road to prevent false misfire codes

39. Code Enable Criteria Definition
“Once the conditions are met to test for the DTC are met, then the monitor will run the test”
P HO2S - 11 Remains At Center (B1 S1) Code Conditions:
Engine runtime over 2 minutes, ECT sensor input more than 176 degrees F, then the test started and the PCM detected that the front HO2S-11 signal was 0.5v (fixed at mid-range for 1 minute)

40. ONE TRIP DTCs
MIL will illuminate after one DTC enable criteria has been met and failed!
Most common One Trip failures are…
Misfire & Fuel Control Monitors
CCM will depending on manufacturer
TPS, MAP, MAF, ECT, CKP, etc.

41. TWO/THREE TRIP DTCs
MIL will illuminate when DTC enable criteria are met and failed in 2 consecutive trips
Compromise for CSI
DTC confirmation

42. TWO/THREE TRIP DTCs When 1st trip fails
Code is “pending” or “maturing”
Freeze Frame data is captured, but not displayed
MIL is off

43. TWO/THREE TRIP DTCs If & When 2nd trip fails…
MIL is illuminated
Code “matures” & DTC is set
Freeze Frame Data can be viewed
Same with 3 trip failures…
Except add 1 trip

44. PENDING DTCs If 2nd trip passes (doesn’t fail)…
Pending Code stays pending for 40 good trips or 80 good trips for misfire / air fuel
Freeze Frame Data is displayed
MIL stays off

45. MIL Strategies & DTCs First Trip Failure
MIL Command:
MIL “bad trip” counter:
MIL “good trips”:
DTC Command:
DTC “bad trips”:
DTC “good trips”
Pending DTC:
Pending “good trips”:
Freeze Frame Data:
Off
One “bad trip”
N/A
Set
Set, but not displayed

46. MIL Strategy Exercise

47. MIL Strategies & DTCs 2nd Consecutive Trip Failure
MIL Command:
MIL “bad trip” counter:
MIL “good trips”:
DTC Command:
DTC “bad trips”:
DTC “good trips”:
Pending DTC:
Pending “good trips”:
Freeze Frame Data: On
Reset to zero
N/A
Set & Displayed
Set or cleared
Displayed

48. MIL Strategies & DTCs 2nd Consecutive Trip Pass
MIL Command:
MIL “bad trip” counter:
MIL “good trips”:
DTC Command:
DTC “bad trips”:
DTC “good trips”:
Pending DTC:
Pending “good trips”:
Freeze Frame Data:
Off
Reset to zero
N/A
Set or cleared
One “good trip”
Displayed or not

49. MIL Strategies & DTCs Fault Repaired / DTC Not Cleared
MIL Command:
MIL “bad trip” counter:
MIL “good trips”:
DTC Command:
DTC “bad trips”:
DTC “good trips”:
Pending DTC:
Pending “good trips”:
Freeze Frame Data: On
Reset to zero
N/A
Set & displayed
Set or cleared
Displayed

50. DTC Priority Designation
Type “A” DTCs
Usually “One Trip” codes
CAT Damaging or 1.5 X FTP
Type “B” DTCs
Usually “2 or 3 Trip” codes
Serious failure
Type “C” & “D” DTCs
Not emission related / won’t illuminate MIL

51. DTC Clearing Automatic Code Clearing Manual Code Clearing
After 40 warm-up cycles with no re-occurrence Or
After 80 warm-up cycles with no re-occurrence for misfire or fuel control codes
Freeze Frame Data gets erased as well
Manual Code Clearing
Through Scan Tool or battery disconnect

52. Common Terminology & Vocabulary
Vernacular Standardization / “New Speak”
Standardization of Terms
ALDL - DLC
EGO - O2S or HO2S
MAT - IAT
Integrator/Block Learn - STFT/LTFT
ESS - CKP

53. FREEZE FRAME DATA The exact second of data that set the DTC
Mandated Data
Calculated Engine Load
Engine Coolant Temperature
Loop Status (open or closed)
STFT / LTFT
Vehicle Speed (mph)
Engine Speed (rpm)
DTC set

54. FREEZE FRAME DATA Freeze Frame Data 1st failed trip of 1st DTC
Not overridden by subsequent DTCs
UNLESS!
Subsequent DTCs are of a higher priority
“A” Type Codes (misfires & fuel control) or a higher priority than “B” Type Codes.

56. DTC / Freeze Frame Exercise

57. OBD II Diagnostics Scan Tool Enhancements
Expanded Information - manufacturer specific
Expanded Description
Troubleshooter - Pathfinder
Identification of Responding PCM
VIN - CAL ID
Vehicle Preparation
Warm-ups, Trips, Drive-cycles

58. OBD II Diagnostics Scan Tool Enhancements (cont’d)
Diagnostic Procedures
Troubleshooter - Pathfinder
Repair Verification
Reset, relearn, adaptive strategies
PID Description & Values
sensor specifications
Test Procedures
Actuators
Miscellaneous

59. OBD II Diagnostics Scan Tool Enhancements (cont’d) DTC Library
code description & enable criteria
O2S location & type
Sensor Simulator
EEPROM Flashing
Replacement PCM Programming

60. OBD II Update Training Course
Session II
OBD II Foundation

61. Session 1 The OBD I Foundation
OBD I - On Board Diagnostics with a Check Engine Light
MIL Operation Inconsistent
DTC Viewing Method Inconsistent
DTC Criteria Inconsistent
DTC Numbering Inconsistent

62. The OBD II System
The Second Generation was designed to fix the inadequacies of the First Generation
One of the biggest problems was the system must be monitored under load!

63. OBD I Mode Monitoring
Degraded emission systems did not set Check Engine Light
EVAP, CAT, & AIR were not monitored
O2S Performance not monitored
CAT killing misfires not monitored
Shifted air fuel ratios not monitored
NOx emissions not monitored (still?)

64. OBD II Strategies Implementation slated for 1996 models
Phase in to begin
OEMs allowed to EEPROM flash to lock-out problems affecting CSI
Check with manufacturer regarding current configuration

65. Setting the Standards C.A.R.B - 1994 - 1998 E.P.A. 1998 - On S.A.E.
Requirements for common systems
Programming changes

66. OBD II Requirements Must be installed on all vehicles
Must be able to determine operating condition of the vehicle’s emission control system / strategy
Diagnostics & Functions must be standardized

67. OBD II Requirements PCM must store DTCs for detected faults
DTC’s must stay in memory until cleared following repair or until 40 consecutive warm-up cycles
80 consecutive warm-up cycles if misfire and/or fuel control related

68. OBD II Requirements
The system must test emission control systems, record the results, and display those results
A MIL is mandatory
must illuminate when a fault is detected (and confirmed?)
must remain illuminated until the fault is corrected (3 tests)

69. OBD II Requirements Generic Scan Tool (GST)
SAE J 1850 and/or ISO 9141 communication protocol
Must monitor ALL OBD II information
Monitoring & DTC clearing procedures must meet CARB & EPA standards
Must display Parameter ID (PIDs)
Freeze Frame Data
PCM Parameters & Test Results

70. OBD II Requirements Monitor Test Results
Comprehensive Component Monitoring
Input Normality & Rationality
Outputs for performance or at least electrically

71. The Scan Tool (2 Tools In One?)
OBD II Generic Scan Tool (GST)
Manufacturer Specific Scan Tool
Hybrid
OBD II Generic with Manufacturer Specific Capabilities

72. OBD II Commonalties Standardization Facilitated by SAE
SAE compromised of Reps from OEMs
OBD II guidelines established by SAE
OEMs interpreted guidelines differently
OBD II is the SAME, but DIFFERENT!

73. Emission Related Monitoring
Unlike OBD I, OBD II not only monitors an actuator was commanded on, but tests the system to make sure it actually worked!!!

74. OBD II Monitors
Designed to detect failures that would cause emissions to increase by 50% or would shorten the life of the catalytic converter
The number of monitors are increasing
Monitors require more computing resources and additional sensors
Monitors are run under specific conditions

75. OBD II TRAINING MODULE
OBD II MAIN MONITORS

76. READINESS TESTS Monitor Run Conditions Readiness Test Criteria
Definition
Conditions that must be met prior to a system or component being tested
Example
Catalyst Monitor Test
ECT > 170°, throttle open, in closed loop, v, VSS over 20 mph

77. READINESS FLAGS Definition
Tells you via Scan Tool if monitor has been completed
Done, Ready, Readiness Test Complete
Does not tell you the outcome!!!
If pass once or twice - no code
If fail once or twice - DTC

78. SYMPTOM WITHOUT CODES Run 2 or 3 drive cycles…
Check for DTCs & Pending DTCs
If no OBD II problems detected then…
Check mechanical, electrical, ignition, emissions, fuel, and any other non computer monitored system

79. OBD II “TRIPS” Definition… Purpose / Objectives
A set of operating conditions to be met in order to run a monitor so that the test is valid and drive-ability is not sacrificed.
Purpose / Objectives
To test a component or system
To verify complaint
To verify repair effectiveness

80. OBD II “DRIVE CYCLES” Definition…
A specific set of operating conditions that enable ALL “trips” to complete and ALL monitors to run

81. OBD II “WARM-UP CYCLES”
Definition…
ECT must begin below and rise above 160° F
ECT must rise at least 40° F
No further faults occur
Sometimes includes CTS and BTS (IAT) be within 10° F of each other
Purpose / Objectives
Erase DTCs & Freeze Frame
Enable criteria for some DTCs & Trips

82. FUEL LEVEL INPUT Fuel Level should be between… If not… For Example…
15% & 85%
25% & 75%
If not…
Some Monitors will not run!
For Example…
EGR, EVAP Leak, EVAP Flow, & Fuel System need fuel level above 15%

83. OBD II Monitors Comprehensive Component Monitor
Catalyst Efficiency Monitor
Misfire Monitor
EGR Monitor
EVAP Monitors
Fuel System Monitor
Oxygen Sensor Monitors
Secondary Air Monitor

84. COMPREHENSIVE COMPONENT MONITOR
Definition…
A continuous look at a lot of something
Sensors - VSS, CKP, KS, TPS, CTS, CMP
Outputs - Any and all outputs that could affect emissions
Checks for “Normality” constantly
Checks for “Rationality” when enable criteria is reached

85. COMPREHENSIVE COMPONENT MONITOR
All “Rationality” checks should be performed in the course of a “Drive Cycle”
DTCs could be 1 or 2 trip codes

86. CATALYST EFFICIENCY MONITOR
Infers Catalyst efficiency by comparing pre & post O2S operation
A working oxidation consumes O2 in order to oxidize HC & CO into Water & CO2
A working catalyst uses Cerium that stores and releases O2 to enhance efficiency

87. CATALYST EFFICIENCY MONITOR
Upstream O2S should oscillate
Downstream activity should not be within 70% of Upstream
Generic Enable Criteria is as follows:
ECT >170°, Closed Loop for at least 3 minutes, RPM between 1,200 & 2,500, Vehicle Speed at least 20 mph for 3 minutes, MAP between 11” - 15” hg, and fuel level over 15%

88. CATALYST EFFICIENCY MONITOR
DTC - P0420
Set when monitor is run and fails
Might be due to defective catalyst
Could be caused by O2S performance, ECT too low, exhaust leak, etc…
This monitor doesn’t check the reduction portion of the catalyst
The upstream & downstream O2Ss are NOT the same!!!

89. MISFIRE MONITOR Misfires result in HC failures
Misfires damage catalysts
Two types of misfires
“A” & “B” misfires
“A” identifying SEVERE misfires
Type “A” misfires might result in MIL flashing

90. MISFIRE DETECTION Relies on CKP Sensor Usually Variable Reluctor
PCM looks for asymmetrical signal
either frequency or amplitude
Some vehicles use Hall-Effect
Some vehicles use a totally separate sensor

91. MULTIPLE MISFIRES DTC - P0300
Random / Multiple Misfire Detected
Usually the cylinder that is misfiring is identified by the code
Depending on the % of time a cylinder is misfiring it will be designated “A” or “B”
Remember - A type “A” misfire will over-write previous Freeze Frame Data!

92. MISFIRE MONITORS “ROUGH ROAD”
Vibration due to rough roads could result in false P0300 DTCs
Some manufacturers refer to wheel speed sensors to verify rough road conditions
If rough road is verified - misfire monitor is suspended.
Faulty wheel speed sensor circuits can prevent misfire monitor
Check OBD I codes first!!!

93. MISFIRE MONITOR DIAGNOSIS
OBD II Misfire Monitor can be more sensitive than an ignition oscilloscope!
Verify misfire with DSO connected to…
CKP or Misfire Sensor and map signal when MIL illuminates
Upstream O2S and map signal within 10% of Freeze Frame Data
O2S won’t tell you which cylinder - just that a misfire is occurring.

94. EGR MONITOR EPA Requirement for monitoring EGR system…
The diagnostic system shall monitor the EGR system on vehicles so equipped for low & high flow rate malfunctions.
Monitoring Alternatives
MAP, O2S, Temperature

95. EGR MONITOR MAP
Manifold Pressure is monitored during EGR system operation to determine flow rate
Usually on deceleration
Monitoring Performed by Pressure Differential Sensor
Same as MAP, but with different name
Lower than expected pressure infers low flow rate. Higher than expected pressure infers excessively high flow rate.

96. EGR MONITOR OXYGEN SENSOR TEST
Energizing EGR system removes O2 from combustion chamber
De-energizing EGR system increases O2 in combustion chamber
PCM monitors how long it takes fuel trim to put O2 back on track to measure flow rate

97. EGR MONITOR TEMPERATURE SENSING
Sensor installed in EGR passage
PCM determines EGR flow rate by monitoring temperature

98. EGR MONITOR ENABLE CRITERIA
Varies from manufacturer to manufacturer
Typical enable criteria as follows:
Closed Loop
Steady cruise (40-55 mph) for three minutes
Deceleration from steady cruise (no braking)
No other DTCs associated with EGR or monitoring system
Usually 2 trip DTC

99. EVAP MONITOR EPA Requirements for monitoring EVAP system…
The diagnostic system shall verify air flow from the complete system. In addition, the diagnostic system shall also monitor the evaporative system for the loss of HC vapor into the atmosphere by performing a pressure or vacuum check of the complete evaporative system. Manufacturers may temporarily disable the evaporative purge system to perform a check.

100. EVAP MONITOR Malfunction Criteria No purge is occurring
A leak = or > 0.040” (0.020” in the future)
MIL Illumination and DTC storage
Usually a 2 trip code
Remember!
Fuel tank must be between 15% & 85% (25% & 75%)

101. EVAP MONITOR Purpose of EVAP system
To store HCs that would have otherwise evaporated into the atmosphere and purge them into the induction system for burning.
A leak = 0.020” will allow 1.35 grams of HCs into the atmosphere for every mile traveled!

102. EVAP MONITOR
All EVAP Monitors require a warm-up cycle! EVAP tested once per drive cycle!
OBD II uses 1 or 2 EVAP system vent solenoids (isolate system)
Differential Pressure Sensors (EGR Monitor?)
reads pressure in inches of water. 1 inch = .25” of mercury (HG)

103. EVAP MONITOR 2 Methods of testing the system for integrity
Vacuum testing
Pressure Testing

104. EVAP MONITOR Vacuum Testing Seal the system Pull a vacuum
Monitor the Differential Pressure Sensor over time

105. EVAP MONITOR Pressure Testing
Seal the system
Pump up a pressure
Monitor Differential Pressure Sensor over time
More accurate than Vacuum Testing because vacuum can sometimes temporarily seal a small leak.

106. EVAP MONITOR Code Enable Criteria Varies manufacturer to manufacturer
One manufacturer’s criteria is as follows:
Fuel tank level is between 15% & 85%
Engine off (soak) time 6 hours minimum
Time since start-up between 330 & 1800 seconds
IAT between 40° & 100° F
BARO (<8,000 ft. altitude), minimum 22.5” HG

107. EVAP MONITOR Code Enable Criteria (cont’d)
Engine Load between 20% & 70%
VSS between 40 & 75 mph
Purge duty cycle between 75% & 100%
Fuel tank pressure between 1.7” & 2.5” H2O

108. EVAP MONITOR Usual DTC’s
P Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction
P Evaporative Emission Control System Leak Detected (Gross Leak)
P Evaporative Emission Control System Leak Detected (Small Leak)

109. EVAP MONITOR FAILURE DIAGNOSIS
Scan Tool EVAP Test
Manufacturers Scan Tool ability
Scan Tool can operate vent solenoids to seal the system
Scan Tool can cycle purge solenoid to pull a vacuum on system and then seal it off
Scan Tool will monitor Differential Pressure Sensor to determine if a leak exists and if it is large or small

110. EVAP MONITOR FAILURE DIAGNOSTICS
Smoke Machine EVAP Testing
Use Scan Tool and seal the system
Open EVAP system and introduce smoke or use schrader adapter (green cap)
CAUTION - watch the pressure!!!
Watch for escaping smoke

111. EVAP MONITOR FAILURE DIAGNOSIS
Dedicated Tester
Pressure pump with gauge that reads inches of water (not mercury)
Doesn’t help in isolating the leak - just verifies there is a leak

112. EVAP MONITOR FAILURE DIAGNOSIS
Gas Analyzer Testing
Isolate / Seal the system as necessary
Pressurize the system
Use gas analyzer as you would a halogen leak detector for AC work
Gas Cap Testers

113. FUEL SYSTEM MONITOR EPA requirements for monitoring Fuel System…
The diagnostic system shall monitor the fuel delivery system for its ability to provide compliance with emissions standards

114. FUEL SYSTEM MONITOR Continuously monitored whenever ignition is on!
Usually type “A” DTCs (one trip)
Relies on fuel trim data directly and O2S data indirectly

115. FUEL SYSTEM MONITOR OBD I Terms Carburetor Dwell Duty Cycle Voltage
Integrator / Block Learn

116. FUEL SYSTEM MONITOR Fuel Trim Values Short Term Long Term
+ % #s mean fuel is being added over base calculations
- % #x mean fuel is being subtracted over base calculations
usually + or - 10% is acceptable

117. OXYGEN SENSOR MONITOR
EPA Requirements for monitoring the Oxygen Sensor…
The diagnostic system shall monitor the output voltage, response rate, and any other parameter which can effect emissions, of all primary (fuel control) oxygen (lambda) sensors for malfunction. It shall also monitor all secondary oxygen sensors (fuel trim control or use as a monitoring device) for proper output voltage and/or response rate

118. OXYGEN SENSOR MONITOR
EPA Requirements for monitoring the Oxygen Sensor (cont’d)…
Response rate is the time required for the oxygen sensor to switch from lean to rich once it is exposed to a richer than stoichiometric exhaust gas or vice versa (measuring oxygen sensor switching frequency may not be an adequate indicator of oxygen sensor response rate, particularly at low speeds)

119. OXYGEN SENSOR MONITOR
EPA Requirements for monitoring the Oxygen Sensor (cont’d)…
For vehicles equipped with heated oxygen sensors, the heater circuit shall be monitored for proper current and voltage drop (note: a continuity check of oxygen sensors is not required)

120. O2S MONITORING 3 TESTS ARE PERFORMED… First test is for calibration.
Is the sensor operating between allowable tolerances?
Second test is switching time.
How long does it take to go from rich to lean or vice versa?
Third test is frequency
O2S activity under normal (?) conditions

121. SECONDARY AIR MONITORING
EPA Requirements for monitoring Secondary Air operation
Any vehicle equipped with any form of secondary air delivery system shall have the diagnostic system monitor the proper functioning of the secondary air delivery system and any air switching valve.

122. SECONDARY AIR MONITORING
Two Common Tests…
1. Widen injector pulse width for a artificially rich condition & monitor O2S. Pump Secondary Air upstream and monitor O2S
2. Monitor STFT / LTFT and pump Secondary Air upstream

123. OBD II UPDATE TRAINING
Round-Up

124. MALFUNCTION INDICATOR LIGHT (MIL)
MIL Status
Off
PCM has not detected any faults in an emission related component or system, or MIL is inop
On Steady
indicates a fault in an emissions related component or system that could affect emission levels
Flashing
misfire or fuel control system fault that could damage catalytic converter

125. MALFUNCTION INDICATOR LIGHT (MIL)
Turning Off the MIL
Codes are cleared through scan tool
Power to PCM is removed
disconnect battery
remove fuse(s)
doesn’t always work
3 consecutive trips are completed without further faults detected

126. SIMILAR CONDITIONS FUEL & MISFIRE
Engine RPM within 375 of stored Freeze Frame Data
Engine Load within + or - 10% of stored Freeze Frame Data
Engine Coolant Temperature similar to stored Freeze Frame Data

127. DIAGNOSTIC TROUBLE CODES (DTCs)
5 Digit - Alpha-numeric DTCs
First Digit (reading from left to right)
Designates either powertrain (P), Body (B), Chassis (C), or Network (U)
Second Digit
Designates DTC as SAE Generic (0) or Manufacturer Specific (1)

128. DIAGNOSTIC TROUBLE CODES (DTCs)
Third Digit
Designates Faulted System
1-Air Metering & Fuel System
2-Fuel System (fuel injector only)
3-Ignition System or Misfire
4-Emission Control System
5-Idle Speed / Vehicle Speed
6-Computer Outputs
7&8-Transmission & Transaxles
Fourth & Fifth Digits
Designates Specific Fault

129. DIAGNOSTIC TROUBLE CODES (DTCs)
DTC Types
“A” - One trip codes
“B” - All Other
DTC Erasure
Scan Tool
Removing Power from PCM (sometimes)
Automatic after 40 warm-up cycles with no further faults detected or 80 warm-up cycles for misfire & fuel system

130. FREEZE FRAME DATA
Definition - a single frame of data that displays at a minimum the following data:
Calculated Engine Load (%)
Engine Coolant Temperature (ECT)
Fuel System Status (OL or CL)
Short Term Fuel Trim (STFT)
Long Term Fuel Trim (LTFT)
Miles Per Hour (MPH)
Engine Speed (RPM)
DTC Set

131. FREEZE FRAME DATA
Captured when either pending or mature DTC is set & MIL is illuminated
Only 1 is stored
For the first DTC only
A misfire of fuel control DTC of a higher priority can overwrite a lower priority Freeze Frame
Only the Freeze Frame will be overwritten - not the DTC!!!

132. FREEZE FRAME DATA Uses…
Diagnostics - to analyze the conditions the vehicle was being operated when the fault appeared
Repair Verification - Fuel System & Misfire MILs can only be turned off after 3 trips under similar conditions

133. FUEL TRIM
The ability of the computer to deviate from the look-up table
A low O2 voltage/lean exhaust will result in the Fuel Trim adding fuel / + % #s
A high O2 voltage/rich exhaust will result in the Fuel Trim subtracting fuel / - % #s

134. EVAP MONITOR
The object of this monitor is to verify canister is being purged and that the systems is not leaking fuel vapors into the atmosphere (0.040 / size leak)
Pressure is done via a Differential Pressure Sensor measuring vacuum or pressure
Purge is done by measuring O2 and/or Fuel Trim
2 trip DTC/MIL

135. O2S MONITOR Tests all Oxygen Sensors O2 Sensors must be calibrated
minimum voltage
maximum voltage
O2 Sensors must react fast
activity
rate of change
2 trip DTC/MIL

136. Oxygen Sensor Location Designation
The lower the number, the closer the sensor to the front of the engine or front of the bank
Bank 1 is where cylinder #1 is
Bank 2 is the other bank
The highest number usually designates the post-O2S

137. COMPREHENSIVE COMPONENT MONITOR (CCM)
Continuous Monitor of emission control related items not specifically monitored by the task manager.
Constantly monitors for opens, shorts, and grounds,
Can monitor rationality if enable criteria is met
DTC’s can be 1 or 2 trip

138. Continuous & Non-Continuous Monitors
Misfire
Fuel System
Comprehensive Component Monitor
Non-Continuous
Catalyst
EGR
EVAP
O2S
O2S Heater
Catalyst Heater
AIR

139. CATALYST MONITOR
Objective is to determine if catalytic converter is operative
Compares the frequency & amplitude of Pre & Post O2Ss (voltage level?)
If Post O2S activity is similar to of Pre O2S
Cat must not be working
O2S might be bad
Conditions needed to operated cat might not be being created
Monitor is run once per trip and DTC is a 2 tripper

140. MISFIRE MONITOR
Objective is to detect misfires that could elevate emission by 50% and/or damage catalyst
Main misfire sensor is engine speed
CKP & CMP
2 types of misfires
Catalyst damaging (severe) - flashing MIL
Misfire that will result in emissions rising 50% above FTP
Enable criteria includes - MAP, RPM, ECT, Start-to-run time, & VSS

141. DEFINITIONS
OBD II - Gov’t regulations that mandate faults that result in a 50% increase in emissions be identified, the operator warned, and diagnostics standardized.
Warm-Up Cycle - Start-to-run where ECT increases 40° F and the temperature rises above 160° F
Rationality - comparing sensor/actuator values against others to determine their calibration

142. GENERIC SCAN TOOLS (GST)
WILLs
Read PIDs
Read Readiness Status
DTC’s
Freeze Frame Data
Connect to any OBD II vehicle
WON’Ts
Be as fast as vehicle specific or Hybrid
Diagnose vehicle for you
Fix vehicle for you

143. TRIPS
Definition
A sequence of events and a set of conditions that must be met for a specific monitor to run
Uses
To test a system to verify a complaint or repair
To turn on or turn off MIL

144. OBD II DIAGNOSTICS
DTCs cannot be verified unless code enable criteria has been met
For OBD II to work correctly all OBD I systems have to be OK
No communication problems can sometimes be diagnosed at the DLC