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Disabling the OBD Port for Free!

Zafi May 14, 2016

  1. Zafi

    Zafi Well-Known Member

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    Today I took out a fuse which allows the car to start, run, drive, stop etc as normal BUT the OBD port no longer works.

    It's free, takes seconds to reverse if you are taking the car for a service etc and will mean the car cannot be stolen by breaking the drivers door glass and reaching in to access the OBD port :)
     
    t8ups, CHEZ and feva like this.
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  3. Darren92

    Darren92 Well-Known Member

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    Not sure why you deleted the previous thread but as I said, it won't stop them stealing the car, it will stall them for a few extra seconds but they'll have come prepared for scenarios like removed or blown fuses.
     
  4. Zafi

    Zafi Well-Known Member

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    But they have to unlock the deadlocked passenger door to access the fusebox without setting off the alarm.

    I read of another method which involves putting 12v onto the K pins so it blows their device, but that's going a bit too far??

    My experience with motorcycle thieves is they leave the scene asap if things are not straighforward and move onto another vehicle. This is even easier with cars as there are so many about.
     
    CHEZ likes this.
  5. Chris90

    Chris90 Active Member VCDS Map User

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    I looked at the fuse diagrams and the fuse powers some other modules in the dash. Hence why I havent recommended removing it until I can look at a new wiring diagram from 2009 onwards as thats where my etka stops.
     
  6. John@ECM-TECH

    John@ECM-TECH Owner Site Sponsor

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    Does anyone have these diagrams for the B8 (obd2, can etc)
     
  7. Chris90

    Chris90 Active Member VCDS Map User

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    Will get my manuals working and post up the diagrams for the B8 and B8.5.
     
    John@ECM-TECH likes this.
  8. Zafi

    Zafi Well-Known Member

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    Well, I have been driving about all over the place and everything works.
     
  9. Craig Norquay

    Craig Norquay Member

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    Care to share the fuse number so we can at least look into it Zafi?
     
  10. Zafi

    Zafi Well-Known Member

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    Yes, passenger side, left bank of fuses, second from top. It's a 10A fuse.
    I popped the fuse out and put it in a vacant slot second from bottom :)
     
  11. Tosseef

    Tosseef New Member

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    How about a latching relay circuit to the OBD live, so it's powered when YOU want it? Simple and effective. Done it loads. ;)
     
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  13. desertstorm

    desertstorm Moderator Staff Member Moderator VCDS Map User Audi A4 Audi Avant Owner Group quattro TDi

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    Looking at Elsa Win there are 2 power fuses for the T16 diagnostic plug.
    The wiring of the plug is here
    T16 diagnostic port wiring.JPG

    The fuse locations on the passenger side.

    Diagnostic plug fuses.JPG

    ST2 fuse 11 is a 10A fuse and ST1 fuse 7 is a 5A fuse. These fuses seem to serve no other purpose than powering the diagnostic socket.

    The 10A fuse is from terminal 30 so direct connection to the battery, the other 5A fuse is an ignition switched live.
     
  14. Dsport

    Dsport Active Member

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    You'd be better popping a blown fuse in there
     
  15. Zafi

    Zafi Well-Known Member

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    Yeah, I will do that. Ta
     
  16. Zafi

    Zafi Well-Known Member

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    Yeah, same as the owners manual, that's why I took out the 10A fuse.
     
  17. Chris90

    Chris90 Active Member VCDS Map User

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    Data bus diagnostic interface, Engine control unit
    J217 - Automatic gearbox control unit
    J533 - Data bus diagnostic interface
    J623 - Engine control unit
    J743 - Mechatronic unit for dual clutch gearbox
    T17b - 17-pin connector, blue
    T17r - 17-pin connector, white
    T20d - 20-pin connector
    T94 - 94-pin connector
    B383 - Connection 1 (powertrain CAN bus, high), in main wiring harness
    B390 - Connection 1 (powertrain CAN bus, low), in main wiring harness
    D159 - Connection (high bus), in engine compartment wiring harness
    D160 - Connection (low bus), in engine compartment wiring harness


    Heres the wiring diagram for the port. Think a lad posted it above, but only a snippet of it. Does look to be different between the 2009 model and the later 2013 model.

    Cant find a actual T16 connector for the plug so god knows whats going on there
     

    Attached Files:

    • OBD.jpg
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    John@ECM-TECH likes this.
  18. John@ECM-TECH

    John@ECM-TECH Owner Site Sponsor

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    Nice one, but you could just ground and power it from behind?
     
  19. Chris90

    Chris90 Active Member VCDS Map User

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    In addition to my post above...Looks like the wiring is the same for 2012/13 onwards



    Data bus diagnostic interface
    J234 - Airbag control unit
    J519 - Onboard supply control unit
    J533 - Data bus diagnostic interface
    ST1 - Fuse carrier 1
    ST2 - Fuse carrier 2
    SD7 - Fuse 7 on fuse holder D
    SD11 - Fuse 11 on fuse holder D
    T16 - 16-pin connector
    T16b - 16-pin connector
    T17b - 17-pin connector, blue
    T17e - 17-pin connector, red
    T20d - 20-pin connector
    T100 - 100-pin connector
    135 - Earth connection 2, in dash panel wiring harness
    687 - Earth point 1, on centre tunnel
    B383 - Connection 1 (powertrain CAN bus, high), in main wiring harness
    B390 - Connection 1 (powertrain CAN bus, low), in main wiring harness
    * - see applicable current flow diagram for airbag
    *2 - see applicable current flow diagram for fuse assignment
    *3 - see applicable current flow diagram for basic equipment
    *4 - Diagnostic connection


    So agreeing with desertstorm above.

    Fuse 7 on Fuse holder 1
    Fuse 11 on Fuse holder 2

    Pictured the fuse diagrams too.


    Should be a handy mod for people to do and saves against buying a OBD protector. As even if the thieves tool can bridge the Terminal 30 and Terminal 15 supplies to link the ignition live, its still not going to work as port is completely dead.
     

    Attached Files:

  20. ub7rm

    ub7rm Active Member

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    Very nice - what MY is your car Zafi?
     
  21. John@ECM-TECH

    John@ECM-TECH Owner Site Sponsor

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    all you need to to is strip the ign live and power it via the rear of the port, then it will work, also you could power the tool separately
     
  22. Chris90

    Chris90 Active Member VCDS Map User

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    I guess it depends how long they are willing to mess about with trying to get the port to work. Most will probably just want a quick and easy plug in and press the button to code new keys. Not try get power to the ports.
     
    feva likes this.
  23. amafzal88

    amafzal88 Member

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    So do you remove both fuses to keep it secure?
     
  24. Chris90

    Chris90 Active Member VCDS Map User

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    I would personally.
     
  25. feva

    feva Well-Known Member

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    You removed both fuses from yours Chris? With no adverse effects?
    Mines the same sort of age as yours.

    Sent from my Note 4 using tapatalk
     
  26. Chris90

    Chris90 Active Member VCDS Map User

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    Havent yet. But might do when I get round to it ( one of those types of jobs)
     
  27. xpoweruk

    xpoweruk S4 B8 Smile Machine Team Ibis saloon Audi S4 quattro

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    Quick question

    Is it possible to remove a fuse that cuts power only when the ignition is off?
    The reason being my P3cars gauge uses the OBD port when the ignition is on
     
  28. Chris90

    Chris90 Active Member VCDS Map User

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    Fuse 11, is constant feed from the battery.

    I imagine tour P3cars device will need both the fuses to work....but its a simple test to pull the fuse and test it.
     
    xpoweruk likes this.
  29. ub7rm

    ub7rm Active Member

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    This seems a great solution. Nothing is full proof, but as said when things don't go to plan with the recode tool chances are the average scrote isnt going to start fault finding. Especially as by then the alarm should be going off and trying to rewire the port, upside down, likely in the dark with no way to open the doors to get at the fusebox is going to put 99.9% off.

    Security film on the front windows should slow them down a good bit too.
     
    CHEZ likes this.
  30. Zafi

    Zafi Well-Known Member

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    2013
     
  31. John@ECM-TECH

    John@ECM-TECH Owner Site Sponsor

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    Seriously 5 min job. Good idea but a proper thief wouldn't be deterred imo
     
  32. xpoweruk

    xpoweruk S4 B8 Smile Machine Team Ibis saloon Audi S4 quattro

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    That could be difference between waking up or not though.
     
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  34. feva

    feva Well-Known Member

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    If there's no power to it, you'd either have to open the doors (which should be deadlocked) or get power to it (which may involve getting into the car and setting off alarm)

    Sent from my Note 4 using tapatalk
     
    John@ECM-TECH likes this.
  35. ammo-mcr

    ammo-mcr Active Member

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    any particular reason why put a blown fuse there...? sorry im new to all this stuff
     
    feva likes this.
  36. feva

    feva Well-Known Member

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    Imo not really. Take them out mark which ones go where, as I've said you'll have to be able to open the doors to get access to fuses.

    Sent from my Note 4 using tapatalk
     
  37. Chris90

    Chris90 Active Member VCDS Map User

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    Also worth tweaking alarm config to go off straight away instead of a delay.
     
  38. AudiLeon

    AudiLeon Well-Known Member VCDS Map User

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    They might just decide to damage the car in anger.
     
  39. Meemo

    Meemo Well-Known Member Supercharged Audi S5 Black Edition

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    no one concerned openly saying they have done this when allot of cars are targeted specifically (Audis especially to order and unique cars here easily recognisable) and they can use your post here to know what to do?
     
  40. feva

    feva Well-Known Member

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    Meemo understand its a public forum but the obd port technique relys on it being live. The obd port protector devices move it the port or locks it, removing fuses makes it no longer live. They would then have to find a way to stop the alarm, bypass deadlocks to open the doors, all of which takes time. The current method they seem to be using is very quick and the more time taken to steal the car the more they are likely to move on.

    Sent from my Note 4 using tapatalk
     
  41. Meemo

    Meemo Well-Known Member Supercharged Audi S5 Black Edition

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    Once you smash the window you can press the unlock button under the window though. Just concerned for everyone is all :)
     
    feva likes this.
  42. feva

    feva Well-Known Member

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    Oh, even with deadlocks active?

    Sent from my Note 4 using tapatalk
     
  43. Meemo

    Meemo Well-Known Member Supercharged Audi S5 Black Edition

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    No idea on dead locks lol not gonna test the theory though :p just careful not too share too much on your cars security incase, I am always quite wary
     
    BenC00 likes this.

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