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P0A1D - HV Control - Replaced - No Ready Light

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by tracy ing, Dec 22, 2017.

  1. tracy ing

    tracy ing Active Member

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    Hi all need some help. Car threw P0A1D indicating one of the two computers under the dash under the passenger air bag was not working. There are I think the engine computer on the left with the hybrid drive computer bolted to it on the right. Triangle of death.
    Bought a HV controller off of ebay with the same part number for 10 bucks. Installed it and threw the dash in the car as far as plugging everything up and tried and had no code anymore but still had triangle of death.

    I checked and found I had not pushed down on the HV batter orange disconnector so I did that and plugged the 12 volt battery back in and tired again.

    The triangle has gone away, the car looks like it is booting up properly, no codes are being thrown, it went into neutral one time and no more. The engine did not ever fire up even with heater on, the ready light has never come on, i stopped trying cause i read something about the immobilizer and turning the car on more than 20 times could foul things up.

    I replaced only the HV drive controller 89981-47123 not the engine ecu to its left, is this ok to do ?
    Is there some trick I still have to do to get the replacement HV Controller to work with the existing engine ECU and or immobilizer ? (like shorting those pins and leaving it on 40 minutes or whatever)

    Although there are no codes the check engine light is on

    Thanks
     
  2. Dxta

    Dxta Senior Member

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    Could you post pictures of the HV controller you said you replaced? Have never heard of such a controller before.
     
  3. Beachbummm

    Beachbummm Senior Member

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    Im not 100% sure but when you replace some computer related parts the dealer has to reset everything so they can communicate properly..even if the part numbers are the same... like the fob.. all the same part number but without programming they don't work.
     
  4. tracy ing

    tracy ing Active Member

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    i cant post links, go to google search for 89981-47123 and click IMAGES

    Behind the glove boxes under the dash have to remove dash there are two computers bolted together, they have to be lifted out towards the windshield. Left one is the engine ecu i think, and the right one is the hv controller, i think its for the transmission, Thats the one I replaced.

    You can see these two computers with all their plugs if you just remove your bottom glove box, it just pops out.
     
  5. bisco

    bisco cookie crumbler

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    welcome! how many miles on her? how is the 12v health?
     
  6. tracy ing

    tracy ing Active Member

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    Hybrid Powertrain Control Module
     
  7. tracy ing

    tracy ing Active Member

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    12 volt fine hundreds of thousands of miles
     
  8. JC91006

    JC91006 Senior Member

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    Can you provide a little history of your car? How the error came about?
     
  9. tracy ing

    tracy ing Active Member

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    Wife was at work car would not go in gear, she sat and sat and two hours went by she got it in gear, left work early came home.

    Parked it here didnt cut it off. I cut it off put it in gear moved forward.

    Cut it off restarted would not start or go in gear threw P0A1D

    Internet said check for moisture in some connectors, that didn't work.

    Another prius came by we swapped everything in the rear of dead car to good car all tested good, battery and all the electronics in the rear.

    Code indicates there is no communications bus and if not a wiring issue the module is bad.

    Replaced the module with exact same part number 89981-47123 and on first boot up it stopped throwing the codes related to the comm bus for the transmission computer

    It still had a triangle but I traced that to the high voltage plug i pulled on the traction battery, wasn't pushed down and locked

    Press brake press ON button twice the check engine light is on with no code, triangle is off, the car icon on display is green, engine does not start and cant place in gear.

    If I move shifter to neutral AS IT BOOTS UP it may go into neutral but thats it, if I wait for full boot up it wont even go into neutral.

    The replaced module cleared the P0A1D code, so I am wondering when that is replaced (its bolted to the engine computer) does some process have to be done to allow it to synch up with the immobilizer. The engine ECU was NOT replaced, only the computer to its righjt that is for the transmission. Hybrid Powertrain Control Module
     
  10. bisco

    bisco cookie crumbler

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    what code reader are you using?
     
  11. Texas Hybrid Batteries

    Texas Hybrid Batteries Senior Member

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    Here are the directions to register the the HV Control ECU with your car. If you don't do this the immobilizer will not let you READY the car. I've always used a paper clip to jumper CG and TC. Remember, your car will have to sit for 30+ minutes running only off of the 12 volt battery so if you have a charger that you can put on it for this procedure it would be a good idea.



    upload_2017-12-23_0-21-20.png
     
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  12. Texas Hybrid Batteries

    Texas Hybrid Batteries Senior Member

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    It's the one that controls the Hybrid System
    upload_2017-12-23_0-30-45.png
     

    Attached Files:

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  13. tracy ing

    tracy ing Active Member

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    Its 3 am, I woke up after charging the battery and started doing this, then came here and saw concurrence that this is what to try. THANK YOU
    In another 15 minutes we will see if this fixed it, and if it does, Ill be in the mountains in the rain putting the dash together so my wife doesnt once again leave in my f 350 7.3 liter turbo powerstroke for a 200 mile round trip commute to work. :)

    Let me add that the pins I jumped resulted in the display going into DIAGNOSTICS MODE so I hope those were the correct pins to jump. BTW the diag mode has three categorys listed and all are green as in passed diags.

    I chose the pins by going to pin 4 on the long edge of the connector and pin 5 on the short edge starting from left looking underneath with long edge being top left
     
  14. tracy ing

    tracy ing Active Member

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    code reader is harbor freight
    Autel AL519 Color Screen OBDII/CAN Scan Tool Graphing DTC Look Up I/M Ready Live Data OBDII Code Scanner

    it show MIL off and no codes on any of the three modules it sees, check engine light is on
     
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  15. Dxta

    Dxta Senior Member

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    Thanks so much for this info. I do understand what it does now, and even where its located.
     
  16. dolj

    dolj Senior Member

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    That leaves 11 or more ECUs it doesn't see, one or more that has set a code.

    Autel make Prius capable readers, perhaps it needs some software updated.
     
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  17. tracy ing

    tracy ing Active Member

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    Guess what ?

    DRUMROLL

    Its working :)

    Ok so first time I tried this the battery died before I got to 30 minutes, I had a 2 6 10 amp small charger set at 6 amps and the battery could have been drained a lot from days of messing about.

    At 6 amps it would not keep up in diag mode, lost 1/100 of a volt a second, at 10 amps it gained 1/100 about every 3 seconds, so I charged it for 8 hours at 6 amps woke up set it at 10 amps and then did the pins using a paperclip for 30 minutes. Ready light is on went in gear moved forward.

    NOW TO SIT IN THE DARK RAIN IN THE MOUNTAINS AND PUT THE DASH IN

    THANKS ALL

    battery made 4-15 and is an expensive optima yellow top
     
  18. Dxta

    Dxta Senior Member

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    Congrats!
     
  19. tracy ing

    tracy ing Active Member

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    Drove 40 miles to town and back all is well THANKS
     
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  20. tracy ing

    tracy ing Active Member

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    OK I AM BACK. MORE PROBLEMS

    So replacing the Hybrid Powertrain Control Module worked for about 6 weeks and thousands of miles, I ended up also replacing the 12 vot battery too last week

    Drove the car last night, parked it, today, its dead again with a new but related code,

    U0293 Lost Communication With Hybrid Powertrain Control Module

    When the car is powered up, ready light never comes on, no triangle is lit, and all of the shift indicators start blinking and the engine fan is on.

    I have three HPCM tried all of them none did anything to alter the symptoms

    When I use my code reader I used to see three different "things" I could talk to to try and pull codes from and I would have to select each one and check for codes., I no longer am offered a choice and am taken straight into the screen where I can choose to read a code.