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Odd OBD2 power issue.

Discussion in 'Automotive Electronics' started by dr pepper, Dec 3, 2015.

  1. dr pepper

    dr pepper Well-Known Member

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    Location:
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    I have a fiat 1.3d multijet, it has obd2, the car has only been in my possesion a couple of weeks.
    I plugged in my usb to obd2 dongle which has a elm327 chip inside, the power light comes on but theres no comms (fiat use can).

    I then tried one of those cheap generic blue obd2 to bluetooth adaptors normally ised for android torque and its doesnt light up, neither does a more expensive maxiscan bluetooth to obd device.
    The diagnostic socket is a git to reach so I cant really get in with a meter to see if theres 12v on pin 16 or not, the fact the usb to obd lights up suggests there is.

    Has anyone elese had anything like this?, I'd really like to use the diagnostics as I have the fiat software for this car, if I ever need to replace a injector or work on the fuel system I'll need it.
     
  2. dr pepper

    dr pepper Well-Known Member

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    Location:
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    Ok I got somewhere.
    Pin 16 isnt battery voltage all the time, somewhere there is a relay that switches it, I thought pin16 was +12 all the time on obd, +12v being interrupted to the bluetooth interface was messing it up.
    The car runs ok so there isnt a fault I know about.
    Powering the adaptor from 12v makes it work fine.
     

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