September 28, 2002 Page 1

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1 An Introduction to Vehicle Networks, Scan Tools, and Multiplexing Presented Haga clic by: para modificar el estilo de subtítulo Paul del Baltusis patrón Powertrain Control System Engineering Diagnostic Systems Department OBD-II Technical Specialist Revised: September 28, 2002 September 28, 2002 Page 1

2 In-Vehicle Networks In-vehicle networking, also known as multiplexing, is a method for transferring data between electronic modules via a serial data bus. September 28, 2002 Page 2

3 Benefits of Networking Eliminates redundant sensors and dedicated wires for each function (lower cost, lower weight, better reliability) Reduces number of wires and connectors (lower cost, lower weight, better reliability, easier-to-package wiring harness) Allows more features and more flexibility (modules share data, more flexible design and vehicle option content) Allows adding features via software upgrades September 28, 2002 Page 3

4 Benefits of Networking September 28, 2002 Page 4

5 Networking Methods Class A Generic UART (Universal Asynchronous Receiver/Transmitter) or other custom low speed device < 10 Kbps. Class B Medium speed, for example J1850, between 10 Kbps and 125 Kbps (Ford DCL and SCP, GM Class 2) Class C High Speed, for example CAN 2.0, between 125 Kbps and 1,000 Kbps (Controller Area Network) September 28, 2002 Page 5

6 OBD Communication Protocols OBD-II and EOBD regulations define the communication protocols that can be used for diagnostics. The intent was to reduce the proliferation of manufacturer-specific protocols used for diagnostics. This would lead to more generic, less expensive scan tools. September 28, 2002 Page 6

7 OBD Communication Protocols ISO (K-Line) ISO (Keyword Protocol 2000) J Kbps Pulse Width Modulated J Kbps Variable Pulse Width J2284/ISO (CAN) September 28, 2002 Page 7

8 OBD Communication Protocols Only one OBD-compliant link may be brought out to the J1962 Data Link Connector OBD-II allows only 500 kbps CAN, EOBD allows 250 and 500 kbps. CARB will force all manufacturers to use CAN for the 2008 MY J2534 (pass through reprogramming) must use a generic OBD link. September 28, 2002 Page 8

9 Controller Area Network CAN is a network protocol used to interconnect a network of electronic control modules or nodes. Typically, a two wire, twisted pair cable is used. CAN has a stringent set of rules, implemented in the CAN chip, that supports the serial transfer of information between two or more nodes. September 28, 2002 Page 9

10 CAN Network Where does CAN fit in the range of networks? Networks are usually based on size: WAN Wide Area Network (Internet) LAN Local Area Network (Ethernet) SAN Small Area Network (CAN) September 28, 2002 Page 10

11 CAN CARB allows the use of CAN for 2003 MY and beyond vehicles. EOBD allows the use of CAN for 2001 CY and beyond vehicles. Some US manufacturers are planning to start using CAN starting on some vehicles in the 2003 MY. CARB requires the use of CAN on all vehicles for the 2008 MY and beyond. September 28, 2002 Page 11

12 CAN CAN messages have a specified structure that is specified in CAN standards. CAN networks have rules (bitwise arbitration) for dealing with colliding messages when two modules start transmitting messages at the same time. There are two formats for addressing 11 bit and 29 bit identifiers. 11-bit has a 2032 message limit, 29-bit allows for millions of distinct messages. September 28, 2002 Page 12

13 CAN Basic Message Structure September 28, 2002 Page 13

14 CAN Message Arbitration September 28, 2002 Page 14

15 J PWM J PWM is used by Ford. Ford internally calls this protocol Standard Corporate Protocol (SCP) SCP is a true network protocol that incorporates bus arbitration. SCP is used for both vehicle network communication and diagnostic communication. September 28, 2002 Page 15

16 J VPW J VPW is used by General Motors. GM internally calls this protocol Class 2. Class 2 is a true network protocol that incorporates bus arbitration. Class 2 is used for both vehicle network communication and diagnostic communication. September 28, 2002 Page 16

17 ISO 9141 ISO 9141 is used by many Japanese manufacturers. ISO 9141 is not a network protocol, it can only be used for diagnostics. There is no bus arbitration. It can be used to connect one diagnostic tool to a vehicle control module. ISO 9141 is relatively slow 10.4 Kbps September 28, 2002 Page 17

18 KWP 2000 KWP is used by many European manufacturers. It uses an enhanced set of diagnostic messages but retains the ISO 9141 physical layer. KWP is not a network protocol, it can only be used for diagnostics. There is no bus arbitration. It can be used to connect one diagnostic tool to one or more vehicle control modules. KWP is relatively slow 10.4 Kbps September 28, 2002 Page 18

19 Types of Network Messages There are two types of network messages Diagnostic messages Normal Mode messages Normal Mode messages are used to share information between modules on the network during normal vehicle operation, e.g. instrument cluster sends fuel level info (percent fill) to PCM. Normal mode messages always use physical addressing. September 28, 2002 Page 19

20 Types of Network Messages Diagnostic Mode messages are used to communicate between a test tool and a module on the network. Diagnostic messages can use either physical addressing or functional addressing. Manufacturer-specific tools normally use physical addressing Generic OBD tools use functional addressing because the configuration of the network and network addresses do not have to be known for every specific vehicle September 28, 2002 Page 20

21 SAE/ISO Diagnostic Specifications Vehicle diagnostic communication specifications have been written by the Society of Automotive Engineers (SAE) and by various International Standards Organization (ISO) workgroups. These standards are referenced by the California, Federal and European OBD regulations. US regulations reference SAE standards, European regulations reference equivalent ISO standards. September 28, 2002 Page 21

22 SAE/ISO Diagnostic Specifications Legislated diagnostics SAE J1930/ISO Electrical/Electronic Systems Diagnostic Terms, Definitions, Abbreviations and Acronyms SAE J1962/ISO Diagnostic Connector SAE J1978/ISO OBD-II Scan Tool SAE J1979/ISO E/E Diagnostic Test Modes SAE J2012/ISO Diagnostic Trouble Codes SAE J2186/ISO E/E Data Link Security Non legislated diagnostics SAE J2190/ISO Enhanced E/E Diagnostic Test Modes September 28, 2002 Page 22

23 SAE/ISO Multiplex Specifications Legislated multiplex standards SAE J1850 (Class B Data Comm. Network Interface) ISO (K-Line) ISO (Keyword Protocol 2000) SAE J2284/ISO (CAN) J2534 Recommended Practice for Pass-Thru Vehicle Programming September 28, 2002 Page 23

24 SAE J1930 Terms and Acronyms J1930 attempts to limit the proliferation of terms, abbreviations and acronyms used in motor vehicle service literature. Examples Ford uses ECT (engine coolant temp sensor), GM uses CTS (coolant temp sensor), J1930 uses ECT Ford uses ISC (idle speed control), J1930 uses IAC (idle air control) Ford uses EEC-V, J1930 uses PCM (powertrain control module) September 28, 2002 Page 24

25 SAE J1930 Terms and Acronyms J1930 describes a consistent methodology for naming components and systems. MODIFIERS BASE WORD What is Where Which What does What Purpose? Is it?temp? it sense? Is it? Sensor (most generic) Temperature Sensor Coolant Temperature Sensor Engine Coolant Temperature Sensor Instrumentation Engine Coolant Temperature Sensor (most specific) Least <<<<<< SIGNIFICANCE>>>>>> Most September 28, 2002 Page 25

26 SAE J1962 Data Link Connector J1962 describes the functional requirements for the vehicle and test tool data link connector (DLC): In-vehicle location/access Connector design Terminal assignments Electrical interface requirements September 28, 2002 Page 26

27 SAE J1962 Data Link Connector The 16-pin DLC assignments are specified in SAE J1962/ISO Pin 1 - Discretionary Pin 9 Discretionary Pin 2 Bus + J1850 Pin 10 Bus J1850 Pin 3 Discretionary Pin 11 Discretionary Pin 4 Chassis Ground Pin 12 Discretionary Pin 5 Signal Ground Pin 13 - Discretionary Pin 6 CAN High Pin 14 CAN Low Pin 7 K-Line ISO9141/KWP Pin 15 L-Line ISO9141/KWP September 28, 2002 Page 27

28 SAE J1962 Data Link Connector The general location of the DLC is specified in J1962, however, CARB and EPA regulations are more restrictive. CARB specifies that DLC must be on driver s side of vehicle centerline, not on center console, or behind storage accessories. A covered DLC must have label (e.g. OBD) approved by CARB. Pin 16 must have < 20 Volts (not 24 or 42 V) September 28, 2002 Page 28

29 SAE J1978 Generic Scan Tool J1978 defines the minimum functionality required by an OBD-II Scan Tool Automatic hands-off determination of the communication interface Displays status and results of on-board diagnostic evaluations Displays pending and confirmed DTCs Displays current data, freeze frame data, and vehicle information Clears DTCs, test results and freeze frame Provides a user manual/help facility September 28, 2002 Page 29

30 SAE J2012 Diagnostic Trouble Codes J2012 defines a set of diagnostic trouble codes (DTCs) where industry uniformity has been achieved. DTCs consist of an alpha character followed by four characters Pxxxx is reserved for powertrain DTCs Bxxxx is reserved for body DTCs Cxxxx is reserved for chassis DTCs Uxxxx is reserved for network DTCs September 28, 2002 Page 30

31 SAE J2012 Diagnostic Trouble Codes The second character designates whether the DTCs and a generic SAE DTC or a manufacturer-specific DTC. P0xxx, P2xxx, P3400, and U0xxx are generic DTCs P1xxx, P30xx, P3100, P32xx and P33xx are manufacturer-specific DTCs The remaining characters designate the system associated with the fault. The characters are hex and can range from 0 F. September 28, 2002 Page 31

32 SAE J2012 Diagnostic Trouble Codes The J2012 committee defines new DTCs on a quarterly basis, based on manufacturer requests. The J2012 committee assigns DTCs in a uniform manner using J1930 terminology. Sample output: P2632 Fuel Pump B Control Circuit / Open P2633 Fuel Pump B Control Circuit Low P2634 Fuel Pump B Control Circuit High P2636 Fuel Pump B Low Flow/Performance September 28, 2002 Page 32

33 SAE J2012 Diagnostic Trouble Codes Sample input: P0A00 Motor Electronics Coolant Temp Sensor Circuit P0A01 Motor Electr. Coolant Temp Sensor Circuit Range / Performance P0A02 Motor Electr. Coolant Temp Sensor Circuit Low P0A03 Motor Electr. Coolant Temp Sensor Circuit High P0A04 Motor Electr. Coolant Temp Sensor Circuit Intermittent / Erratic Sample network DTCs: U0001 High Speed CAN Communication Bus U0101 Lost Communication with TCM U0302 Software Incompatibility with TCM September 28, 2002 Page 33

34 SAE J2186 Data Link Security J2186 defines a method to access secured vehicle controller functions. Three parameters control security access the seed (sent by controller) and key (sent by external device) the delay time (minimum delay time between attempts) the number of false access attempts September 28, 2002 Page 34

35 SAE J1979 Diagnostic Test Modes SAE J1979/ISO defines standard diagnostic test modes. Diagnostic/emission critical control modules must implement these diagnostic test modes. They must be on the OBD data link or must use another module as a gateway. CARB defines engine and transmission control modules as emission-critical. September 28, 2002 Page 35

36 SAE J1979 Diagnostic Test Modes Any other control module that performs a major OBD-II monitor or performs CCM monitoring for more than two components is considered to be diagnostic critical. If a diagnostic/emission critical control module is reprogrammable, it must respond with Mode $09 CALID and CVN. It must be able to be reprogrammed using a SAE J2534 interface. September 28, 2002 Page 36

37 SAE J1979 Diagnostic Test Modes J1979 specifies a set of standard messages that can be used by scan tool to obtain OBD- II data from a vehicle. (Modes $01 to $09) Functional addressing is used instead of physical addressing for all messages because the test tool does not know which systems on the vehicle have the OBD information that is requested. Response times to messages are specified. Message lengths are specified. September 28, 2002 Page 37

38 SAE J1979 Diagnostic Test Modes Messages must utilize a standard set of header bytes specified for each communication protocol. The remainder of the message (the data bytes) specify the type of message (test mode) and specific data that is being requested. Header byte definitions are specified on the next two slides. September 28, 2002 Page 38

39 SAE J1979 Header Bytes H e a d e r b y t e s C A N f r a m e d a t a f i e l d CAN Identifier (11 or 29 bit) #1 PCI Byte #2 #3 #4 #5 #6 #7 #8 September 28, 2002 Page 39

40 SAE J1979 CAN Header Bytes C A N i d e n t i f i e r ( h e x ) D e s c r i p t i o n ( b i t a d d r e s s i n g ) 7 D F C A N i d e n t i f i e r f o r f u n c t i o n a l l y a d d r e s s e d r e q u e s t m e s s a g e s s e n t b y t h e e x t e r n a l t e s t e q u i p m e n t. 7 E 0 P h y s i c a l r e q u e s t C A N i d e n t i f i e r f r o m t h e e x t e r n a l t e s t e q u i p m e n t t o E C U # 1 7 E 8 P h y s i c a l r e s p o n s e C A N i d e n t i f i e r f r o m E C U # 1 t o t h e e x t e r n a l t e s t e q u i p m e n t 7 E 1 P h y s i c a l r e q u e s t C A N i d e n t i f i e r f r o m t h e e x t e r n a l t e s t e q u i p m e n t t o E C U # 2 7 E 9 P h y s i c a l r e s p o n s e C A N i d e n t i f i e r f r o m E C U # 2 t o t h e e x t e r n a l t e s t e q u i p m e n t 7 E 2 P h y s i c a l r e q u e s t C A N i d e n t i f i e r f r o m t h e e x t e r n a l t e s t e q u i p m e n t t o E C U # 3 7 E A P h y s i c a l r e s p o n s e C A N i d e n t i f i e r f r o m E C U # 3 t o t h e e x t e r n a l t e s t e q u i p m e n t 7 E 3 P h y s i c a l r e q u e s t C A N i d e n t i f i e r f r o m t h e e x t e r n a l t e s t e q u i p m e n t t o E C U # 4 7 E B P h y s i c a l r e s p o n s e C A N i d e n t i f i e r f r o m E C U # 4 t o t h e e x t e r n a l t e s t e q u i p m e n t 7 E 4 P h y s i c a l r e q u e s t C A N i d e n t i f i e r f r o m t h e e x t e r n a l t e s t e q u i p m e n t t o E C U # 5 7 E C P h y s i c a l r e s p o n s e C A N i d e n t i f i e r f r o m E C U # 5 t o t h e e x t e r n a l t e s t e q u i p m e n t 7 E 5 P h y s i c a l r e q u e s t C A N i d e n t i f i e r f r o m t h e e x t e r n a l t e s t e q u i p m e n t t o E C U # 6 7 E D P h y s i c a l r e s p o n s e C A N i d e n t i f i e r f r o m E C U # 6 t o t h e e x t e r n a l t e s t e q u i p m e n t 7 E 6 P h y s i c a l r e q u e s t C A N i d e n t i f i e r f r o m t h e e x t e r n a l t e s t e q u i p m e n t t o E C U # 7 7 E E P h y s i c a l r e s p o n s e C A N i d e n t i f i e r f r o m E C U # 7 t o t h e e x t e r n a l t e s t e q u i p m e n t 7 E 7 P h y s i c a l r e q u e s t C A N i d e n t i f i e r f r o m t h e e x t e r n a l t e s t e q u i p m e n t t o E C U # 8 7 E F P h y s i c a l r e s p o n s e C A N i d e n t i f i e r f r o m E C U # 8 t o t h e e x t e r n a l t e s t e q u i p m e n t September 28, 2002 Page 40

41 Ford Module Addresses Module Phys Adr Func Adr Rec Adr Xmit Adr Func Rec Adr Func Xmit Adr (J1850) (J1850) (CAN) (CAN) (CAN) (CAN) PCM$10 $6A $7E0 $7E8 $7DF $7E8 (Powertrain Control Module) TCM$18 $6A $7E1 $7E9 $7DF $7E9 (Transmission Control Module) ABS $28 $6A $7E2 $7EA $7DF non-obd (Anti-lock Brake System) AHCM $0F $6A $7E3 $7EB $7DF non-obd (Auxiliary Heater Control Module) TCCM $18 $6A $7E4 $7EC $7DF non-obd (Transfer Case Control Module) AFCM $16 $6A $7E5 $7ED $7DF $7ED (Alternative Fuel Control Module) SPCM $11 $6A $7E6 $7EE $7DF $7EE September 28, 2002 Page 41

42 Mode $01 Retrieve Diagnostic Data Mode $01 provides diagnostic data, commonly called PIDs (Parameter ID) Service technicians can use the data to troubleshoot sensors, check OBD monitor completion, MIL status, etc. Test tool specifies the requested data by PID number ($00 through $FF) PIDs are defined in J1979 (number, units, conversion/scaling factor, acronym) PIDs must show raw values not substituted values if a sensor fails September 28, 2002 Page 42

43 Mode $01 Retrieve Diagnostic Data The message format used to make a PID request is as follows: September 28, 2002 Page 43

44 PID $01 I/M Readiness September 28, 2002 Page 44

45 PID $02 and $03 September 28, 2002 Page 45

46 PIDs $04 - $11 September 28, 2002 Page 46

47 PIDs $12 - $1B September 28, 2002 Page 47

48 PIDs $1C - $1E September 28, 2002 Page 48

49 PIDs $1F - $2B September 28, 2002 Page 49

50 PIDs $2C - $33 September 28, 2002 Page 50

51 PIDs $34 - $3F September 28, 2002 Page 51

52 PID $41 September 28, 2002 Page 52

53 PIDs $42 - $4E September 28, 2002 Page 53

54 Mode $02 Freeze Frame Mode $02 stores Mode $01 PID data at the time a pending or confirmed DTC is stored. Fuel system and misfire DTCs have a higher priority and overwrite any existing data. Service technicians can use the data to understand the conditions at the time the malfunction occurred. Only one frame ($00) is required to be stored. September 28, 2002 Page 54

55 Mode $02 Freeze Frame Freeze frame can be useful, however, there are some caveats. Freeze frame is stored when the DTC is stored, not when the problem began. For circuit faults, it usually takes 5 seconds to store a DTC. Misfire is evaluated every 1,000 revs. A misfire DTC may be stored seconds after the misfire initially occurred, at substantially different rpm and load conditions. September 28, 2002 Page 55

56 Mode $02 Freeze Frame The message format used to retrieve freeze frame is as follows: September 28, 2002 Page 56

57 Mode $03 Retrieve emission-related DTCs Mode $03 reports confirmed, emission-related DTCs. Service technicians and I/M test stations use this mode to determine what malfunction turned on the MIL. Mode $03 reports history codes for 40 warm-ups after the MIL is extinguished. September 28, 2002 Page 57

58 Mode $03 Retrieve emission-related DTCs The message format used to retrieve emission-related DTCs is as follows: September 28, 2002 Page 58

59 Mode $04 Clear DTCs and Diagnostic Information Mode $04 clears/erases DTCs and resets diagnostic data at the time a pending or confirmed DTC was stored. Diagnostic data includes freeze frame, I/M readiness, monitor status, PIDs for MIL_DIST, WARM_UPS, CLR_DIST, Mode $06 data. Service technicians can use this mode to turn off the MIL after a repair and to validate a repair. September 28, 2002 Page 59

60 Mode $04 Clear DTCs and Diagnostic Information The message format used to clear DTCs is as follows: September 28, 2002 Page 60

61 Mode $05 Retrieve Oxygen Sensor Data Mode $05 provides test results for oxygen sensors. This mode is no longer used for CAN applications. All data is still available using Mode $06. September 28, 2002 Page 61

62 Mode $05 Retrieve Oxygen Sensor Data The message format used to retrieve oxygen sensor data is as follows: September 28, 2002 Page 62

63 Mode $05 Retrieve Oxygen Sensor Data D a t a D e s c r i p t i o n B y t e 2 W h i c h T e s t I D : $ T e s t I D s s u p p o r t e d - o p t i o n a l ( $ 0 1 t o $ 2 0 ) $ R i c h t o l e a n s e n s o r t h r e s h o l d v o l t a g e ( c o n s t a n t ) $ L e a n t o r i c h s e n s o r t h r e s h o l d v o l t a g e ( c o n s t a n t ) $ L o w s e n s o r v o l t a g e f o r s w i t c h t i m e c a l c u l a t i o n ( c o n s t a n t ) $ H i g h s e n s o r v o l t a g e f o r s w i t c h t i m e c a l c u l a t i o n ( c o n s t a n t ) $ R i c h t o l e a n s e n s o r s w i t c h t i m e ( c a l c u l a t e d ) $ L e a n t o r i c h s e n s o r s w i t c h t i m e ( c a l c u l a t e d ) $ M i n i m u m s e n s o r v o l t a g e f o r t e s t c y c l e ( c a l c u l a t e d ) $ M a x i m u m s e n s o r v o l t a g e f o r t e s t c y c l e ( c a l c u l a t e d ) $ T i m e b e t w e e n s e n s o r t r a n s i t i o n s ( c a l c u l a t e d ) $ 0 A - $ 1 F - r e s e r v e d $ T e s t I D s s u p p o r t e d - o p t i o n a l ( $ 2 1 t o $ 4 0 ) September 28, 2002 Page 63

64 Mode $06 Retrieve OBD test results and malfunction limits Mode $06 provides monitoring test values and malfunction limits for various OBD monitors. Service technicians can use the data to see which monitors failed and by how much, or to validate repairs. Parts manufacturers can use this data to ensure replacement part compatibility. September 28, 2002 Page 64

65 Mode $06 Retrieve OBD test results and malfunction limits Mode $06 test values and limits are un-scaled, decimal numbers in J1850, ISO and ISO Manufacturers need to provide conversion factors for technicians to utilize this data. ISO messages provide units and scaling as part of the message. Generic scan tools will be able to convert these to engineering units September 28, 2002 Page 65

66 Mode $06 Retrieve OBD test results and malfunction limits The message format used to retrieve OBD test results is as follows: September 28, 2002 Page 66

67 Mode $06 Retrieve OBD test results and limits J1979 Secondary Air Mode $06 Data Test ID Comp ID Description for J1850 Units $30 $11 HO2S11 voltage for upstream flow test and rich limit volts $30 $21 HO2S21 voltage for upstream flow test and rich limit volts $31 $00 HO2S lean time for upstream flow test and time limit seconds Monitor ID Test ID Description for CAN Units $71 $80 HO2S11 voltage for upstream flow test and rich limit volts $71 $81 HO2S21 voltage for upstream flow test and rich limit volts $71 $82 HO2S lean time for upstream flow test and time limit seconds Conversion for Test ID $30: multiply by to get volts Conversion for Test ID $31: multiply by to get seconds September 28, 2002 Page 67

68 Mode $06 Retrieve OBD test results limits September 28, 2002 Page 68

69 Mode $06 Retrieve OBD test results limits September 28, 2002 Page 69

70 Mode $06 Retrieve OBD test results limits September 28, 2002 Page 70

71 Mode $06 Retrieve OBD test results limits September 28, 2002 Page 71

72 Mode $06 Retrieve OBD test results limits September 28, 2002 Page 72

73 Mode $06 Retrieve OBD test results limits September 28, 2002 Page 73

74 Mode $06 Retrieve OBD test results limits J1979 DPFE EGR Hose Check Mode $06 Data Test ID Comp ID Description for J1850 Units $42 $11 Delta pressure for upstream hose test and threshold in. H 2 0 $42 $12 Delta pressure for downstream hose test and threshold in. H 2 0 Conversion for Test ID $42: Take value, subtract 32,768, and then multiply result by to get inches of H 2 0. The result can be positive or negative. Monitor ID Test ID Description for CAN Conventional DPFE $31 $80 Delta pressure for upstream hose test and threshold kpa $31 $81 Delta pressure for downstream hose test and threshold kpa J1979 EGR Flow Check Mode $06 Data Test ID Comp ID Description for J1850 Units $49 $30 Delta pressure for flow test and threshold in. H 2 0 $4B $30 EVR dutycycle for flow test and threshold percent Conversion for Test ID $4B: multiply by to get percent dutycycle. Conversion for Test ID $49: Take value, subtract 32,768, then multiply result by to get inches of H 2 0. The result can be positive or negative. Monitor ID Test ID Description for CAN Conventional DPFE Units $31 $85 Delta pressure for flow test and threshold kpa September 28, 2002 Page 74

75 Mode $06 Retrieve OBD test results and malfunction limits Example of Mode $06: TestID CompID Test Value Min Max $10 $11 Cat monitor switch ratio Bank 1 $10 $21 Cat monitor Switch ratio Bank 2 Conversion: multiply by to get a value from 0 to 1.0 Bank 1 = 45 * = Bank 2 = 42 * = Threshold = 48 * = This catalyst is about to fail. A normal 100K catalyst should have a 0 to 0.1 September 28, 2002 Page 75

76 Mode $07 Retrieve pending DTCs Mode $07 reports pending, emission-related DTCs. Starting in the 2005 MY, all pending DTCs must be reported, not just continuous pending DTCs. Staring in the 2005 MY, a pending DTC must be reported if the last monitoring cycle had a malfunction. Service technicians can use pending codes for faster validation or a repair. September 28, 2002 Page 76

77 Mode $07 Retrieve pending DTCs The message format used to retrieve pending, emission-related DTCs is as follows: September 28, 2002 Page 77

78 Mode $08 Request on-board device control Mode $08 allows a service technician to invoke an on-board test mode. Only one test mode (Test ID $01) is currently defined. It allows a service or an I/M technician to seal the evaporative system for a pressure test. On Ford systems, this closes the canister vent solenoid for a 10 minute time duration. September 28, 2002 Page 78

79 Mode $08 Request on-board device control The message format used to request on-board device control is as follows: September 28, 2002 Page 79

80 Mode $09 Retrieve vehicle information Mode $09 allows a service tech or I/M test technician to obtain vehicle VIN, module calibration number (CALID), Calibration Verification Number (CVN). VIN is required for 2005 MY, the vehicle can only report one VIN. CALID is required for 2005 MY. A unique CALID is required for each emissionrelated calibration on the vehicle. A unique CALID is required even if only a bit if data changes. September 28, 2002 Page 80

81 Mode $09 Retrieve vehicle information (continued) A CVN must be supplied for each CALID In 2005 MY, CVN must be calculated every driving cycle and stored in Keep Alive Memory so that it can be retrieved with the engine off or engine running. CVN must not be erased by Mode $04. CARB must approve CVN algorithm. Manufacturers must provide CALID and CVN information to facilitate I/M testing. September 28, 2002 Page 81

82 Mode $09 Retrieve vehicle information (continued) Starting in the 2005 MY, CARB will require industry-standard counters that display how often OBD monitors run during real-world driving conditions as compared to a CARBspecified driving cycle. In-use performance counters will be required for catalyst, O2 sensor, EGR, secondary air, and evaporative system monitors. September 28, 2002 Page 82

83 Mode $09 Retrieve vehicle information The message format used to retrieve vehicle information is as follows: Info Type $02 is VIN, $04 is CALID(s), $06 is CVN(s), $08 is in-use performance counters September 28, 2002 Page 83

84 Inspection/Maintenance Readiness Many I/M test facilities will soon (Jan 1, 2002) be using OBD-II diagnostic information in place of tailpipe emissions tests. They will check MIL lamp, MIL status bit (PID 01, Data A, bit 7) and OBD monitor readiness (PID 01). For 2005 MY, they may check VIN, CALIDs and CVNs September 28, 2002 Page 84

85 Inspection/Maintenance Readiness (continued) CALIDs ensure that the correct (not recalled) software is on the vehicle. CVNs ensure that the module software was not tampered with. MIL status must not indicate MIL on during bulb prove out unless the MIL is being commanded on by a confirmed DTC. Monitor readiness bits must be in Keep Alive Memory September 28, 2002 Page 85

86 Inspection/Maintenance Readiness (continued) I/M readiness status may be displayed to the customer using the MIL. After seconds of MIL prove out, the MIL can blink for 5-10 seconds if the vehicle is not ready for I/M testing. For the 2005 MY, CARB will require a scan tool communication validation of every production calibration using a J tool. September 28, 2002 Page 86

87 SAE/ISO Diagnostic Specifications Non-legislated diagnostic messages are defined by SAE J2190 and ISO These are commonly referred to manufacturer-specific test modes. Manufacturers can use these messages to perform manufacturer-specific tests and obtain manufacturer-specific data from any control module. Almost all manufacturers provide this info to the Equipment and Tool Institute (ETI), the consortium of scan tool manufacturers. September 28, 2002 Page 87

88 SAE/ISO Diagnostic Specifications Common uses for these messages are: Obtain manufacturer-specific PIDs Initiate on-board self-test Obtain packets of PID data (rapid data) Control module outputs Reprogram flash memory Configure modules The J2190 messages are very similar to the J1979 messages in structure and content. Only physical addresses are used, responses are required. September 28, 2002 Page 88

89 J2190 Mode $13 Mode $13 reports all DTCs (emission and non-emission, confirmed and pending.) Very similar to Mode $03 Data Bytes (Hex) #1 #2 #3 #4 #5 #6 #7 Request all codes Request all powertrain DTCs (MIL, non-mil, pending) 13 Report all codes Report all powertrain DTCs (MIL, non-mil, pending) 53 Code #1 or Code #2 or Code #3 or No codes to report, exit normally without results General Response 7F September 28, 2002 Page 89

90 J2190 Mode $14 Mode $14 clears all DTCs. Very similar to Mode $04 Data Bytes (Hex) #1 #2 #3 #4 #5 #6 #7 Request clear codes Request clear all codes, (MIL, non-mil, pending) Confirm codes clear Confirm all codes were cleared (individual clearing of codes not supported) No codes to report, exit normally without results General Response 7F 14 data byte #2 data byte # September 28, 2002 Page 90

91 J2190 Mode $22 Mode $22 is used to get PIDs. PID numbers, scaling and units are defined by manufacturer and are specific to their individual systems. Very similar to Mode $01 Data Bytes (Hex) #1 #2 #3 #4 #5 #6 #7 Request data by PID Request PID Access 22 PID (high byte) PID (low byte) Report data by PID Report PID Data 62 PID (high byte) PID (low byte) data 1 (opt) data 2 (opt) data 3 (opt) data 4 (opt) Invalid PID requested, request not supported General Response 7F 22 data byte #2 data byte # September 28, 2002 Page 91

92 J2190 Mode $23 Mode $23 is used to download data by direct memory address. Test tool gets raw data. Data Bytes (Hex) #1 #2 #3 #4 #5 #6 #7 Request data by DMR Request DMR Access EEC-V 23 address (high byte) address (mid byte) address (low byte) Report data by DMR Report DMR Data EEC-V 63 address (high byte) address (low byte) data 1 (opt) data 2 (opt) data 3 (opt) data 4 (opt) Invalid DMR requested, request not supported General Response 7F 23 address (high byte or high word MSB) address (mid byte or high word LSB) September 28, 2002 Page 92

93 J2190 Mode $2A Mode $2A is used to get a string of PIDs in one message; a rapid packet. Used with Mode $2C to define rapid packet. September 28, 2002 Page 93

94 J2190 Mode $30 Mode $30 is used to directly control module outputs like shift solenoids, IAC, AIR pump, EGR, etc. (requires Mode $27 security access) Data Bytes (Hex) #1 #2 #3 #4 #5 #6 #7 Perform parameter substitution Parameter Substitution 30 Chann. ID Subst. Value high byte Subst. Value low byte Confirm diagnostic routine entered General Response 7F 30 Chann. ID Subst. Value high byte Subst. Value low byte 00 Invalid conditions, test running, or test not supported General Response 7F 31 Test # , 22, 33, or 12 September 28, 2002 Page 94

95 J2190 Mode $31 Mode $31 is used to request an on-board test, based on test number. Test Number On-demand Self Test Mode $81 Key On Engine Off (gas and diesel) $82 Key on Engine Running (gas and diesel) $84 Output Test Mode (gas and diesel) $88 Key On Engine Running Glow Plug Test (diesel) $91 Key On Engine Off Injector Buzz Test (diesel) $92 Key On Engine Running Cylinder Contribution Test (diesel) $95 Key On Engine Data Bytes Running (Hex) Switch Test (diesel) #1 #2 #3 #4 #5 #6 #7 Perform diagnostic routine by test number Diagnostic Routine Entry 31 Test # Confirm diagnostic routine entered General Response 7F 31 Test # Invalid conditions, test running, or test not supported General Response 7F 31 Test # , or 12 September 28, 2002 Page 95

96 J2190 Mode $36 Mode $36 is used for reprogramming. (requires Mode $27 security access and Mode $34 Download Entry request) Data Bytes (Hex) #1 #2 #3 #4 #5 #6 #7 Request to enter download mode Download Block Data 36 data 1 data 2 or 00 data 3 or 00 data 4 or 00 data 5 or 00 data 6 or 00 Not in download mode General Response 7F 36 data 1 data 2 data 3 22 September 28, 2002 Page 96

97 J2190 Mode $3F Mode $3F is used to indicate that the test tool is still online and prevent a diagnostic session time-out. Data Bytes (Hex) #1 #2 #3 #4 #5 #6 #7 Tester Present Tester Present 3F Acknowledge tester General Response 7F 3F September 28, 2002 Page 97

98 J2190 Mode $7F Mode $7F is used by the control module to respond to a test tool request. Data Bytes (Hex) #1 #2 #3 #4 #5 #6 #7 General acknowledge General Response 7F Data byte #1 of request Data byte #2 of request Data byte #3 of request Data byte #4 of request Acknowledge or Reject Code: Ackn or Reject code $00 - General affirmative $10 - General reject $11 - Mode not supported $12 - Invalid format, sub-function not supported $21 - Busy, repeat request $22 - Condition not correct, sequence error $23 - Routine not complete $31 - Request out of range $33 - Access denied, device secured $34 - Access granted $50 - Upload not accepted $61 - Normal exit with results $62 - Normal exit without results $63 - Abnormal exit with results $64 - Abnormal exit without results September 28, 2002 Page 98

99 J1979 Message Traffic Example Clear DTCs (Mode 04) TX MSG: J1850PWM 61 6A F1 04 RX MSG: J1850PWM 01 6B Request PIDs (Mode 01) [PID $00 defines which PIDs are supported ] TX MSG: J1850PWM 61 6A F RX MSG: J1850PWM 01 6B BF 9F B9 10 Request PID 04 (LOAD_PCT) TX MSG: J1850PWM 61 6A F RX MSG: J1850PWM 01 6B [LOAD_PCT = 0%] Request PID 05 (ECT) TX MSG: J1850PWM 61 6A F RX MSG: J1850[PWM 01 6B A [ECT = 74 deg F] Request PID 11 (TP) TX MSG: J1850PWM 61 6A F RX MSG: J1850PWM 01 6B [TP = 19%] Request PID 1C (OBD Type) TX MSG: J1850PWM 61 6A F1 01 1C September 28, 2002 Page 99

100 J1979 Message Traffic Example Request Mode 09 info TX MSG: J1850PWM 61 6A F RX MSG: J1850PWM 01 6B FC [request Mode 09 items supported] TX MSG: J1850PWM 61 6A F RX MSG: J1850PWM 01 6B [number of VIN messages = 5] TX MSG: J1850PWM 61 6A F RX MSG: J1850PWM 01 6B RX MSG: J1850PWM 01 6B RX MSG: J1850PWM 01 6B RX MSG: J1850PWM 01 6B RX MSG: J1850PWM 01 6B [item 02 = VIN] [VIN = 1FTYR44E72TA31978] Request Pending DTCs (Mode 07) TX MSG: J1850PWM 61 6A F1 07 RX MSG: J1850PWM 01 6B [Pending DTC P0113, P0102 detected] September 28, 2002 Page 100

101 J1979 Message Traffic Example Request Freeze Frame Support (Mode 02) [PID $00 defines which PIDs are supported ] TX MSG: J1850PWM 61 6A F RX MSG: J1850PWM 01 6B F Request Freeze Frame PID 02 TX MSG: J1850PWM 61 6A F RX MSG: J1850PWM 01 6B [DTC that stored frame = P0113] Request DTCs (mode 03) TX MSG: J1850PWM 61 6A F1 03 [No response to OBD request, no DTCs] Request DTCs (Mode 03) TX MSG: J1850PWM 61 6A F1 03 RX MSG: J1850PWM 01 6B [Stored DTC P0113 detected] September 28, 2002 Page 101

102 The End I hope this presentation took some of the mystery out of diagnostic scan tool communication. Thank you for your interest and attention! September 28, 2002 Page 102