After Head Gasket replacement, wont start & codes... help?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Jmcclusk, Oct 22, 2021.

  1. Jmcclusk

    Jmcclusk Junior Member

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    Sorry about another thread about head gaskets, I just am having trouble now and read tons of threads and checked everything twice... and still no answer, help?

    I have a 2011, 165k miles, just was starting to have the dreaded startup rattle knock, so I got a new head gasket and kit and head bolts and watched all the videos and went through it very carefully and cleaned everything very well. I checked the head was flat and the block, and that all cylinders were coming up to full height. I cleaned the throttle body, EGR pipes and valve. I reassembled following everything in the service pages to a T and even after it was together, I triple checked the timing was correct after the chain tensioner was unhooked and pushing on it. I traced the wiring harness and plugged in every single plug, the three on the back, the 4 on the front lower water pump area, the fuel injectors, and all the ones on the valve cover. I filled with oil (not overfilled) and filled red coolant and kept up at full line.

    When I first got it in it, the screen just said check hybrid system without starting, so I checked everything and the 12v battery was pretty low and old so I bought a new one and installed it. Then it would try to start but:

    Trying to start was rough 5 seconds and never started up, just threw codes and said check hybrid system. Engine Codes P0123, P2135, P3191 and HV Battery ECU: P0A0F

    Tried doing it 4 times, but nothing gets better. I took stuff apart and checked it and put it back together, and no change. The one odd thing is the throttle body makes this whining noise after the engine has given up trying to start. eeeeeeeeeeeee. like its fighting itself or something or maybe thats normal. The P0123 and P2135 are throttle body errors so maybe that has to do with it? Any ideas?

    I can post pictures of the timing, and of the Dr. Prius error codes if you want. Thank you
     
  2. Jmcclusk

    Jmcclusk Junior Member

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    I checked compression by turning the crank with a ratchet and could get about 90-100 on all cylinders. I know its supposed to be higher, but I was just turning it by hand so it wasn't full start speed.

    I also checked all the fuses, and none were blown.

    Unfortunately the traction battery is down to 207v or ~15% SOC so kinda screwed here unless there is a real fix to confidently start it in one or two more tries. Thanks for any insights
     
  3. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Try Dr Prius phone app. Carista OBD dongle is an option that works. Just doing the simple, static test, with the car “on” (not “ready”)* it’ll give info about voltage and resistance of the 14 blocks.

    * Two pushes of Start button without pushing brake pedal
     
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  4. JC91006

    JC91006 Senior Member

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    Are you sure there's gas in the car?

    Running the HV battery low will be a big problem. You may need to find a way to charge that up if you can't figure out the problem fairly quickly. A low charge on a 10 year old battery is prime candidate for a battery failure (low charge and balance issues)
     
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  5. Jmcclusk

    Jmcclusk Junior Member

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    Thank you for your responses.
    Yes, I have the Dr. Prius app and thats how I got the codes and see the state of charge is getting lower. It is turning the engine over, so it has power supplied, its just not getting fuel or spark or something?

    Yes, there is gas, its got a half tank and when I took the fuel rail off the injectors to check everything after the first unsuccessful start there was fuel pressure, it squirted out a bit.

    I agree, I'm not wanting to try starting it again till I change something meaningful, but don't know whats next. Replace the throttle body/throttle position sensor? I'm not in a town that has a Toyota dealership, closest one is an hour away. Thanks for your thoughts
     
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  6. Jmcclusk

    Jmcclusk Junior Member

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    so my responses have taken awhile to get approved. I ran out of possibilities and dont have a full Techstream and pc laptop so could only get the top level errors. I gave up and I sent it to Maxat Hybrid Repair place in Sacramento. Towing sucked but at least they'll be able to charge the traction battery and diagnose the problem. I'll report back what they find if it might be useful to the community or others in the future.
     
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  7. ChapmanF

    ChapmanF Senior Member

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    You could follow the troubleshooting steps in the repair manual (more info) for those two codes, possibly finding an issue in the wiring or connection to the throttle body. They both have to do with the position feedback signal that comes from the throttle body back to the ECM. The TB sends two redundant signals of its position, and the ECM checks that the two are in the right relationship to each other. P0123 meant the VTA1 voltage is too high, and P2135 is about the wrong voltage relationship between VTA1 and VTA2.

    The eeeeeeeeeeeee itself is normal. The ECM's signal to position the throttle is a pulse train at a frequency you can hear. That's what it sounds like. Points to you for correctly locating it at the throttle body—many people who notice that sound and post about it mistakenly assume it's coming from something else, like the inverter.
     
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  8. Jmcclusk

    Jmcclusk Junior Member

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    So just in case someone reads this later and wonders what happened, the Maxat Hybrid Repair in Sacramento ended up fixing it. They wouldn't really tell me what the problem was, just said it needed the timing cover resealed and there was nothing wrong with any of the electronics. So $1258 later, it runs but I don't know why. I watched all the videos and service documents and have picture proof the timing was right even after the chain tensioner was on there, and was meticulous about cleaning and making sure it was all flat and torque sequences were followed... so I do not know. Maxat Hybrid Repair did the job right away and quickly, but basically no feedback on "why" so just gotta pay it and move on. (I looked at it and they did in fact reseal it, I can see the slight difference in sealant color. Oh well. Thanks to anyone who tried to help.
     
  9. JC91006

    JC91006 Senior Member

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    So basically you forgot to do something simple and they can’t really tell you what you forgot to do. Very strange you can’t get an answer on what was wrong
     
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