Engine shakes after replacing head gasket but no consistent codes

Discussion in 'Gen 3 Prius Technical Discussion' started by oldzebra, Sep 26, 2025.

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  1. oldzebra

    oldzebra New Member

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    Thank you very much, that helps a lot.
     
    #21 oldzebra, Oct 14, 2025 at 5:26 PM
  2. oldzebra

    oldzebra New Member

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    I back probed the cam sensor to start. I'm not sure what values I should have gotten. Here are the readings, Do these readings look like what they should look like?

    Voltage:
    White to black wire: +4.1V falling to .71V when a metal object is held to the end of the sensor
    Red to Black: .89V
    Red to White: 5.02V

    Ohms:
    R to White: 1.35K Ohms
    R to Black: 1.29K Ohms

    Thanks
     
    #22 oldzebra, Oct 14, 2025 at 9:25 PM
  3. rjparker

    rjparker Tu Humilde Sirviente

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    It would help to know the code. However to check for an open you measure each wire for ohms from one end to the other with the ecm disconnected and powered off. Typically you want 1 ohm after accounting for meter lead ohm readings by themselves. You then check each wire to chassis which should be higher than 10k.

    See attached
     

    Attached Files:

    #23 rjparker, Oct 14, 2025 at 10:19 PM
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  4. oldzebra

    oldzebra New Member

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    I'll hook up techstream today to verify that the code is actually what my reader says it is. Based on this forum, generic readers, like the ones I have, are less than reliable.

    I'm not very good at troubleshooting car electrical issues. Thanks for explaining clearly what I should do. If the code is still there with tech stream I'll go from the ECU to the cam wiring to check for an open.
     
    #24 oldzebra, Oct 15, 2025 at 1:07 PM
  5. rjparker

    rjparker Tu Humilde Sirviente

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    I suspect you don't have an "open" cam sensor based on your voltage reading changes, even though they were not exactly what the manual suggests.

    These three codes each have one possibility for an open circuit but have other options for mechanical timing issues, which are more common.

    IMG_0323.jpeg

    This video covers the timing chain positioning in detail. A problem that has happened is use of the wrong marks. This link jumps to that section. The whole video shows the rest of the process except rotating the chain counterclockwise to release the tensioner.

    Sane Auto w jump to Cam Timing Marks
     
    #25 rjparker, Oct 15, 2025 at 1:51 PM
    Last edited: Oct 15, 2025 at 7:54 PM
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  6. oldzebra

    oldzebra New Member

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    Techstream was harder to get working than I thought, mostly because my cable, a OBDLink EX is not fully J2534 compliant. So I ordered another cable that, allegedly, is. Wish there was a higher quality (non-chinese) option for a J2534 compliant cable but I can't find one. Probably take a week to get here.

    What you're saying makes sense, thank you for explaining it to me. I'll pull the valve cover again tomorrow and check that the timing is correct per that video, and hasn't jumped. I actually followed that video when doing the timing, I think it was in of the posts on here, possibly one of yours in another thread. It may have jumped or I may have made a mistake somewhere. I'll try to post pictures when I get the valve cover off and the intake cam turned so the timing lines up with the marks again.

    Thanks again for the help
     
    #26 oldzebra, Oct 16, 2025 at 4:13 AM
  7. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Here you go.

    The Tactrix OpenPort 2.0 is a very high quality interface developed by a small team in the USA. They build an excellent product and they offer first rate support for it. They cost more, but that's how it works.
     
    #27 Leadfoot J. McCoalroller, Oct 16, 2025 at 9:28 AM
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  8. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Searching for Tactrix OpenPort 2.0 I get a lot of amazon.ca results, with prices from $50~100 CDN. And this, apparently from the Tactrix official site:

    Tactrix Openport 2.0

    Showing a price of $169 USD

    I'd gather the latter is the real thing, the Amazon offerings not so much?
     
    #28 Mendel Leisk, Oct 16, 2025 at 12:19 PM
  9. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I'm aware that the product has been counterfeited, but I've done no research on how to tell a real one from a fake one. Price is probably a good indicator though.

    I bought mine direct from Tactrix years ago.
     
    #29 Leadfoot J. McCoalroller, Oct 16, 2025 at 12:21 PM
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