Burnt up battery ecu replaced now P0A0F engine fail to start

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ozmatt, Dec 29, 2020.

  1. ozmatt

    ozmatt Active Member

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    Hi everyone hope you are all doing well and very happy new year to you all from little old down under.!!.. it's been a while since I needed to post because really I just don't get many prius issues that I can't chop through with laptop and coffee but I really don't fancy fighting with this for too long if someone here can kindly help cut the chase :)

    Rundown: nearly a battery fire, picked up a dirt cheap 08 that broke down on the owner and got dumped at a dealership a few months ago because the battery and ecu repair price significantly outweighed the vehicles value, back of the car was (and had been for a while) full of water around all the usual places.. I am very familiar with battery rebuild process and have literally tons of spares so figured it's an easy project for me, ..yeah right lol

    anyway i threw in another lazy but still functional hv pack (has some corrosion but it works in another car (tested today in a wrecked car)) as a temporary way just to get it home as it really needs to be moved from where its sitting and sorted out properly, unfortunately the bloody stupid thing still has multiple codes relating to engine won't start which I can't help but directly relate to the original burnt up battery ecu possibly spiking something else, maybe engine ecu or hybrid control ecu? or dragging the car to move it as it was stuck in park but I doubt that's the problem because it goes in and out of park fine and the engine winds over and tries to start, the old battery ecu is properly toasted, checkout the pics below..

    So the car will "ready" and attempts to start the engine for the default 8 or 10 seconds (sounds like its running but its just the cvt winding the engine) then PROBLEM on mfd and all the codes, after this happens it won't stay "ready" for more than about a second unless i reset codes with the laptop reset 12v and repeat the whole process, Its full of fuel and i can smell fuel when it tries to start, there is no water in oil. The thermo fan runs nearly instantly when (cold) engine is winding, Maf is dry.

    The codes:

    (Hybrid control)
    *P0A0F - 204
    *P3000
    *P3102 - 581

    (Engine and ECT)
    *P3190

    (HV Battery)
    *P0A80
    *P0AFA

    & the usual couple abs/vsc codes associated with p0A80 that I won't bother to list

    After resetting the car and going through all the motions again and again I basically get most of the above straight back but sub-codes can vary and 3102 seems to have gone away, for now anyway.

    I keep thinking about the engine fan starting on a cold engine nearly from the get-go .. seems a bit like a sus engine ecu?


    Any help muchly appreciated please chime in if you have a clue :)

    Cheers :)

    Matt






    View attachment 203098 IMG_20201229_102433_235.jpeg

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    #1 ozmatt, Dec 29, 2020
    Last edited: Dec 29, 2020
  2. ozmatt

    ozmatt Active Member

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  3. TMR-JWAP

    TMR-JWAP Senior Member

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    The last P0A0F-204 I worked on, ended up being the throttle body. Pull the MAF sensor out of it, clean both the MAF and the TB really well, verify the electrical plug is making good contact. Then it fired right up.

    You can try just pushing the butterfly plate open and closed a few times with a screwdriver, as that may free things up enough to at least get it fired up.

    Then again, it could be something totally different for your situation. You just never know. Three requirements....air, fuel and spark. Mine just happened to be the air portion.
     
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  4. ozmatt

    ozmatt Active Member

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    cheers TMR i will check the TB and clean or replace the maf tomorrow

    i have another known working and fully charged pack to take with me and will grab a drum of fuel too just to be sure because P3190 can only really mean so many things, i can smell fuel while its cranking and its reading 10 pips of fuel but not sure if i should trust it, the cars been sitting a few months and i have no solid history on it ..

    btw ignore the 3102 we had the P lock relay out to keep neutral and move the car around, of course once i put the relay back that code went away
     
  5. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    It can be very difficult to troubleshoot a non running Prius engine. You seem to be on the right tract. Newbies fall into the trap of chasing the hybrid battery. You have correctly avoided that quicksand. There is not one and only one cause for a non running engine. The last thread similar to yours was caused by diesel fuel in the gas tank. I have also seen water in the gas disable a Prius. The most common cause is a dirty MAF sensor. You have already checked that.

    Try to start the car with some starting fluid. Clear the codes before the starting attempt. Remember, air, fuel, spark. A little starting fluid and you will know if fuel is the problem.
     
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  6. ozmatt

    ozmatt Active Member

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    Cheers Strawbrad wish i seen this before i went to the car earlier! you're all over it

    It only took 5 litres /about a gallon of fuel before it poured out the filler, meh! -- cheap car full of fuel, bonus!

    Checked for injector pulse & spark... all good, prob not the engine ecm/ecu

    Spray alcohol down TB and it sits there running,

    Swapped out the integrated fuel pump relay under bonnet aka hood, still no dice ..

    If i was a gambeling man i would say its happened like this .... the car was actually still running with that battery (P0A80 & P3000 etc) previous owner was just clearing codes to "READY" and driving

    ....then he ran out of fuel, kept trying to "ready" it, filled tank .. wouldnt go so had a meltdown!! towed ($1000 car) to dealership - $5000 quote for repairs, on $1000 car.. Abandon

    Will try a new fuel pump tomorrow
     
    #6 ozmatt, Dec 30, 2020
    Last edited: Dec 30, 2020
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  7. ozmatt

    ozmatt Active Member

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    all sorted threw a fuel pump in today and away it went! thanks again for you're help Strawbrad :)

    BTW in Australia we dont have the bladder tank and fuel pump is easily serviceable via access plate under rear seat

    Cheers all have a good and safe new year!
     
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