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B2799-539 Code

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by mailbxs, Sep 14, 2015.

  1. mailbxs

    mailbxs Junior Member

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    2006 Prius
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    I replaced my HV ECU and engine control unit. Now I get a B2799-539 code. Can anyone help? I just bought the mini-vci thinking I could program the vehicle VIN number into the new engine control unit, but I can figure out how to do that.

    I have a 2006 Prius.
     
    #1 mailbxs, Sep 14, 2015
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Vehicle:
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    Two
    DTC B2799 means that the immobilizer ECU has a communications problem. The problem is because the transponder key ECU does not recognize the newly installed hybrid vehicle ECU. I hope that you have not powered up the car 20x or more since you installed the HV ECU - if you did then the transponder key ECU will need to be replaced.

    To get the communications ID to be registered, first disconnect the 12V battery for 30 seconds or more. Then reconnect the battery and insert the fob into the dash slot.

    Insert a jumper wire to short pins 4 and 13 of the OBD-II connector. (There are many posts on finding those pins, make sure you short the correct pins.) Hook up a battery charger to the 12V battery because you are going to leave the car IG-ON for 30 minutes and you do not want the battery to die on you while this is happening. Make the car IG-ON and leave for 30 minutes.

    Come back to the car, make it IG-OFF, remove the jumper, and then try to make the Prius READY.

    Why was it necessary to replace the engine and HV ECUs?
     
    #2 Patrick Wong, Sep 15, 2015
    Last edited: Sep 15, 2015
    Juan Lujan and m.wynn like this.
  3. Samuel sundermeyer

    Samuel sundermeyer New Member

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    I think I’m having this problem currently can you tell me why it is I would have to replace it? Is the transponder key ecu damaged now?
     
    #3 Samuel sundermeyer, Jul 14, 2020
    Last edited by a moderator: Jul 15, 2020
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