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

ECM replacement and reprogramming?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by AZ_2005_PRIUS, Dec 3, 2016.

  1. AZ_2005_PRIUS

    AZ_2005_PRIUS New Member

    Joined:
    Dec 3, 2016
    10
    1
    0
    Location:
    Flagstaff, AZ
    Vehicle:
    2005 Prius
    Model:
    N/A
    Hi I have a 2005 Prius and had all the dash warning lights light up like a Christmas tree. I took it into the local dealership and they said the ECM is bad and I need a new one to the tune of $800. My question is, can I just buy a used one off ebay ($50) and replace it? Or does it need to be reprogrammed by the dealer?

    Thanks!
     
  2. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
    16,464
    8,377
    0
    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    Which ecm module? Most can be purchased off eBay
     
  3. AZ_2005_PRIUS

    AZ_2005_PRIUS New Member

    Joined:
    Dec 3, 2016
    10
    1
    0
    Location:
    Flagstaff, AZ
    Vehicle:
    2005 Prius
    Model:
    N/A
    I didn't get a part number from the dealership (they just said ECM) and they are closed now for the rest of the weekend but I'm assuming its this: ENGINE COMPUTER CONTROL UNIT 89661-47070. But I see on Ebay there about half a dozen different part numbers for this same part:
    PART NUMBER: 89661-47070

    COMPATIBLE PART NUMBERS:

    8966147070
    8966147071
    8966147072
    8966147100
    8966147101
    8966147102
    8966147103
    8966147104

    Do these need to be reprogrammed by the dealer or can I just swap it out?
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,198
    6,461
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    You can swap a used engine ECU into your Prius. I suggest you should be cautious about installing an ECU with a different part number as that newer model might assume the hybrid vehicle ECU has firmware not available in 2005.

    However, I would question whether the engine ECU actually needs to be replaced since the failure rate is quite low.

    Also, although the cost of a used ECU is minimal (due to the low failure rate) you have to disassemble much of the dashboard for access. So there is significant labor content and this is not something you want to casually do.
     
  5. AZ_2005_PRIUS

    AZ_2005_PRIUS New Member

    Joined:
    Dec 3, 2016
    10
    1
    0
    Location:
    Flagstaff, AZ
    Vehicle:
    2005 Prius
    Model:
    N/A
    Ok thanks for your help. These are the codes they gave me:
    P0A0F
    P0A7A
    P0A92
    P0AA6
     
  6. valde3

    valde3 Senior Member

    Joined:
    Jun 28, 2014
    2,002
    745
    0
    Location:
    Finland
    Vehicle:
    2004 Prius
    P0A0F – Engine failed to start
    P0A7A - GENERATOR INVERTER PERFORMANCE Generator inverter fail (GFIV) signal detection
    P0A92 - HYBRID GENERATOR PERFORMANCE
    P0AA6 - high voltage system has a ground fault

    Those codes can’t be produced by faulty engine control unit. Faulty HV-control unit could cause most of them but that still seems very unlikely.

    These codes have sub codes and other freeze frame information with them that could be useful. For example: if 12V battery voltage seems low on them then theoretically that could be the only reason the codes showed up.
     
  7. AZ_2005_PRIUS

    AZ_2005_PRIUS New Member

    Joined:
    Dec 3, 2016
    10
    1
    0
    Location:
    Flagstaff, AZ
    Vehicle:
    2005 Prius
    Model:
    N/A
    Well I found out that the dealership meant HV ECM instead of the "engine ECU" like they originally told me. So I bought a used one off of ebay and replaced it yesterday. I also purchased techstream and a cable and I reset the codes. Now the ICE will not turn on at all (turned on before I replaced HV ECM) and I'm getting an error code B2799 which I believe is an engine immobilizer. I tried to reset the codes and that code just immediately re-appears after I erase codes and re-scan. I'm pulling my hair out. Thoughts?
     
  8. Texas Hybrid Batteries

    Texas Hybrid Batteries Senior Member

    Joined:
    Sep 7, 2014
    270
    549
    3
    Location:
    Dallas -Fort Worth
    Vehicle:
    2006 Prius
    Model:
    N/A
    There's an initiation procedure that has to be done when you swap the hv ecu. You have to jumper 2 of the pins on the obd port and then turn the car on (acc mode, not READY) for 30 minutes so that the immobilizer will pair with the new hv ecu. There's a post somewhere about it.

    Make sure your 12 volt is good or better yet put a trickle charge on it while your doing this.
     
    Catherine Kourouklis likes this.
  9. Texas Hybrid Batteries

    Texas Hybrid Batteries Senior Member

    Joined:
    Sep 7, 2014
    270
    549
    3
    Location:
    Dallas -Fort Worth
    Vehicle:
    2006 Prius
    Model:
    N/A
  10. AZ_2005_PRIUS

    AZ_2005_PRIUS New Member

    Joined:
    Dec 3, 2016
    10
    1
    0
    Location:
    Flagstaff, AZ
    Vehicle:
    2005 Prius
    Model:
    N/A
    awesome, thanks for the info! I'll give it a try and let you know if it fixes my problem.
     
  11. AZ_2005_PRIUS

    AZ_2005_PRIUS New Member

    Joined:
    Dec 3, 2016
    10
    1
    0
    Location:
    Flagstaff, AZ
    Vehicle:
    2005 Prius
    Model:
    N/A
    No luck. I threw a battery charger on the battery to make sure it was topped off, then disconnected the battery for 30 sec, hooked a battery tender up, jumpered the 4 and 13 pins with a paper clip, pushed the power button (no foot on the brake), left the car for 30+ min then pushed the power button again, then one more time to shut the car off. Tried turning the car back on and still no ICE. I hooked up my techstream again and got the same code B2799 (sub code 539). One thing I did notice is when I pulled the sub code, my 12v battery had dropped to 11.28v even while hooked to the battery tender. I'm not sure if that is a problem or not, or if I'm doing something wrong. Thanks for your help![​IMG]
     
  12. AZ_2005_PRIUS

    AZ_2005_PRIUS New Member

    Joined:
    Dec 3, 2016
    10
    1
    0
    Location:
    Flagstaff, AZ
    Vehicle:
    2005 Prius
    Model:
    N/A
    Screen shot
     

    Attached Files:

  13. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    what is the 12v reading with everything off and when cold? and how old is it?
     
  14. dolj

    dolj Senior Member

    Joined:
    May 14, 2012
    7,447
    3,751
    0
    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    You need to be in IG-ON mode, which is two presses of the the power button with the foot OFF the brake.
    While this is not great, as long as it holds the voltage above 11.0 V, it should not be a problem. But, it is time to retire that battery and replace with a new one.
     
    Catherine Kourouklis and valde3 like this.
  15. AZ_2005_PRIUS

    AZ_2005_PRIUS New Member

    Joined:
    Dec 3, 2016
    10
    1
    0
    Location:
    Flagstaff, AZ
    Vehicle:
    2005 Prius
    Model:
    N/A
    Update: I replaced the 12v battery and got the imobilizer code to go away (Thanks dolj for the tip about pressing the button twice!). I'm still getting my original code P0A7A-325 which is Generator inverter performance. I have replaced both the inverter and the HV ECU with used parts. I'm sure there is a chance I got a bad part but I hope that is not the case. After I clear codes, I can drive the car for a little while before the warning lights come on. It seams that the warning lights come on when I accelerate then I can feel the ICE cut out right when the warning lights come on. Also, it seams the whenever the ICE is on the it makes a whining/whirring sound. I'm not sure if the inverter coolant pump has been replaced but I do see turbulence in the tank. Thanks again for all your help!
     
  16. valde3

    valde3 Senior Member

    Joined:
    Jun 28, 2014
    2,002
    745
    0
    Location:
    Finland
    Vehicle:
    2004 Prius
    Have you checked the freeze frame data for that code? Have you checked the fault finding chart for that code: http://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/repair%20manual/04pruisr/05/21bpm/0a7a325.pdf
    Unfortunately first steps requires a milliohm and megaohm meters but other than that chart looks pretty simple.

    Pretty much what you’re left with is faulty replacement part (unlikely) problem with installation of the part(s) (unlikely), wiring, or transaxle.
     
  17. edthefox5

    edthefox5 Senior Member

    Joined:
    Jul 25, 2007
    10,096
    4,795
    0
    Location:
    Clearwater, Florida
    Vehicle:
    2007 Prius
    Model:
    Two
    Bad Hybrid battery. POA6 trumps all other codes. take the hybrid battery out and see how corroded it is in there.

    And has the car ever lost its Hybrid Cooling Pump the one you referenced? And if so has the Inverter overheated because of that event?

    Your resetting that fault code by disconnecting the 12 volt. That whining in the engine may be the engine is doing all the work without any hybrid battery participating. You can confirm that by the battery meter on the mfd or the Inverter may be screaming as the hybrid battery is bad.

    How many miles?
     
    #17 edthefox5, Dec 17, 2016
    Last edited: Dec 17, 2016
  18. AZ_2005_PRIUS

    AZ_2005_PRIUS New Member

    Joined:
    Dec 3, 2016
    10
    1
    0
    Location:
    Flagstaff, AZ
    Vehicle:
    2005 Prius
    Model:
    N/A
    I don't suspect its the hybrid battery. I had it removed and checked for bad cells about 6 months ago. Also the display shows the hybrid battery charging when its parked and the ICE is on.
    My next plan of attack is to go through the chart valde3 referenced to be more sure of the transaxle but it definitely seams like the culprit at this point. I'll let you know what I find! Thanks again for all the help!

    The car has 185k miles
     
  19. 05PreeUs

    05PreeUs Senior Member

    Joined:
    Oct 1, 2016
    1,097
    563
    0
    Location:
    MSP
    Vehicle:
    2005 Prius
    Model:
    N/A
    P0AA6 is a problem, the "system" will/may not allow vehicle operation with that DTC active and it is *possible* to be due to a defective HV ECU.
     
  20. valde3

    valde3 Senior Member

    Joined:
    Jun 28, 2014
    2,002
    745
    0
    Location:
    Finland
    Vehicle:
    2004 Prius
    I thought this message meant that only code now is the P0A7A-325: