1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Replaced HV ECU and now key doesn’t work

Discussion in 'Gen 2 Prius Technical Discussion' started by Samuel sundermeyer, Jul 14, 2020.

  1. Samuel sundermeyer

    Samuel sundermeyer New Member

    Joined:
    Jun 8, 2020
    4
    0
    0
    Location:
    Eureka california
    Vehicle:
    2008 Prius
    Model:
    II
    I replaced my hv ecu on my 2008 Prius In hopes that it would fix everything that was wrong with it. This was before I got the techstream software and the obd2 chord. I don’t know if the old one was bad or not... but I read on another post that if you replace the hv ecu the smart key won’t work and you will have to recalibrate it by shorting the 4 and 13 nodes in the obd2 port and waiting 30 minutes but if you put in IG-ON mode too many times before you do that then you will need a new key transponder ecu. Wel I did start it a bunch of times before reading that post and I tried the recalibration and it didn’t work. I’m wondering now if the hv ecu was bad in the first place and I’m wondering if I put the old one back in then maybe The key will work again. I’m getting code b2799-539. Here is a link to the post I’m referencing. B2799-539 Code | PriusChat

    I would really appreciate any advice and explanations anyone could give me.
     
    #1 Samuel sundermeyer, Jul 14, 2020
  2. edthefox5

    edthefox5 Senior Member

    Joined:
    Jul 25, 2007
    10,096
    4,817
    0
    Location:
    Clearwater, Florida
    Vehicle:
    2007 Prius
    Model:
    Two
    Are you referring to the ecu inside the big hybrid battery in the back of the car?
     
    #2 edthefox5, Jul 15, 2020
  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    24,912
    16,215
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The Hybrid Vehicle ECU is the orchestra conductor for the car. It is not inside the battery, it is closer to the front of the cabin.

    When replaced, it has to be introduced to the car's immobilizer ECU in a specific way.
     
    #3 ChapmanF, Jul 15, 2020
  4. Samuel sundermeyer

    Samuel sundermeyer New Member

    Joined:
    Jun 8, 2020
    4
    0
    0
    Location:
    Eureka california
    Vehicle:
    2008 Prius
    Model:
    II
    So is there a way to do that or do I need to replace the immobilizer ecu?
     
    #4 Samuel sundermeyer, Jul 15, 2020
  5. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    24,912
    16,215
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    There totally is, it's in the repair manual (more info). If you replaced the other ECU you'd still have to do it.
     
    #5 ChapmanF, Jul 16, 2020
(You must log in or sign up to post here.)