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Thread: Help on ELM327 - KWP2000

  1. #11
    Variable Bitrate
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    Oct 2008
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    376
    Well, you are looking at the Alfa specific protocol, which is NOT compliant with OBD2 or EOBD. It is KWP2000, but there are soooooo many versions of this protocol.
    80 at the beginning is header start without any length info, which means byte 4 is the length. The 01 3 byte further is the length of the data following.
    There's only one byte which is 81. This is the wakeup command.

    Now officially Alfadiag shoud have send 81 10 F1 81 cs, because at that moment it is not known that the ecu will support the long headers, but it seems to work.

  2. #12
    Newbie
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    Apr 2009
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    Great.. now the packet is discovered If I make the ELM operete this way I get connection!! Now I know what I have to configure.. thanks A LOT mate!!!!! How did you learn so mutch specific data like this? By time and experience or u had access to SAE and ISO documents ? Thanks again.

  3. #13
    Variable Bitrate
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    I have had access to SAE and ISO documents as well as manufacturer documents.
    I worked for 10 years in developing after-market scanners.

  4. #14
    Newbie
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    Apr 2009
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    That's a position of privilegie and you seem to mesure no effort to help ppl like me, that's an exemple witch everybody should follow. Knowlgment is made to pass and receive, not to keep.
    Thanks again.

  5. #15
    Newbie
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    Apr 2009
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    Updating Solution:

    To solve this problem is very simple:
    Just issue this comand to ELM327: AT SH 8010F1
    SH = Set Header, it will use the proper header for the non OBD KWP2000 of Alfa romeos.
    Tested and it is initializing comunication.

    Thanks to p2psmurf.

  6. #16
    VENDOR - ScanTool Vitaliy's Avatar
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    Quote Originally Posted by fanl View Post
    Updating Solution:

    To solve this problem is very simple:
    Just issue this comand to ELM327: AT SH 8010F1
    SH = Set Header, it will use the proper header for the non OBD KWP2000 of Alfa romeos.
    Tested and it is initializing comunication.

    Thanks to p2psmurf.
    Are you able to get any useful data from the vehicle?
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
    Need to look up a diagnostic trouble code? Try the most up-to-date, free DTCsearch.com!

    You cannot send me a private message using this forum. Use my email instead: vitaliy[@]scantool.net.

  7. #17
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    Apr 2009
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    I got a string of bytes that were not the tipical awnser like it is suppose to be.
    I expected something starting with 41 01.. but i got F7 or 70 as fst byte.. I must try again to get the precise information. As soon I get it tested again I'll post.

  8. #18
    VENDOR - ScanTool Vitaliy's Avatar
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    Quote Originally Posted by fanl View Post
    I got a string of bytes that were not the tipical awnser like it is suppose to be.
    I expected something starting with 41 01.. but i got F7 or 70 as fst byte.. I must try again to get the precise information. As soon I get it tested again I'll post.
    My guess is that the first byte was actually 7F (negative response)?

    Vitaliy
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
    Need to look up a diagnostic trouble code? Try the most up-to-date, free DTCsearch.com!

    You cannot send me a private message using this forum. Use my email instead: vitaliy[@]scantool.net.

  9. #19
    Newbie
    Join Date
    Apr 2009
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    hello ppl! Follow the communication I had with the car.. help me understanding it.
    Code:
    ELM327 v1.3a
    
    >at sh 8010f1
    OK
    
    >at tp 5
    OK
    
    >0001
    BUS INIT: OK
    7F 00 11 
    
    >01
    NO DATA
    
    >0002
    NO DATA
    
    >0101
    NO DATA
    
    >at cp
    ?
    
    >at pc
    OK
    
    >at sp 5
    OK
    
    >0001
    BUS INIT: OK
    7F 00 11

  10. #20
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    Apr 2009
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    another string that "worked"

    Code:
    >8101
    BUS INIT: OK
    C1 EF 8F
    another...

    Code:
    >1800ff00
    58 03 11 72 62 11 73 21 D6 00 A8

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