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Help! Might have bought a lemon?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by bdb3011, Nov 16, 2019.

  1. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    +1. I got an old Asus netbook at a pawn shop and made it the garage computer. Barely takes up any room on the shelf, always ready to go and I don't care about greasy paws on the keycaps. My Mac stays clean in the house.
     
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  2. JC91006

    JC91006 Senior Member

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    I'm going with the assumption your code reader is not giving you all the codes. I want to know from your original post, why your car would allow you to limp home after 15 minutes rest? Possibly after it cooled down? Possibly not related to throttle body at all? This car shuts down most electronic components when it overheats.

    Or maybe you can take a peak inside the throttle and maybe clean it out and the MAF sensor while you're in there?
     
  3. ChapmanF

    ChapmanF Senior Member

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    I don't think it's especially easy for even a cheapo scan tool to get a P0 code wrong. If it says there are P0121 and P0122 codes set, probably that's because there are, so I'll go with the problem turning out to have something to do with janky signals getting back to the ECM from the throttle body.

    As covered upthread, whether that means the throttle body itself is the reason the signals are janky is not something the ECM or a code reader will be able to reveal; where the actual trouble is in that circuit will be for some human to suss out.
     
  4. Skibob

    Skibob Senior Member

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    I’m interested in finding out if it’s the throttle body or something else. OP please keep us advised. I agree with lead foot on an old laptop. You only need a single core windows 7 machine to run Techstream, that’s a pretty low and cheap bar these days. You actually don’t want it connected to the internet when you are running the program, and if the battery is weak just use an extension cord to power it.
     
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  5. bdb3011

    bdb3011 Junior Member

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    Thank for all the advise. My plan is to replace the throttle body (mainly because I had already ordered it before some of your comments) and if that doesn't resolve the issue get a cheap laptop and the software.

    Also, in response to the couple overheating comments: I'll look into that, however I don't think it's the issue as the car will commonly throw the two codes immediately after start up in the morning. So it's happened when it's warm, slightly warm, and cold.

    Thanks everyone, i'll keep ya posted.
     
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  6. Skibob

    Skibob Senior Member

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    You really should get the software and a cheap laptop even if the throttle body works. Then you have it the next time you need it. It also works on all Toyota’s, I use it on my others whenever I have a problem.
     
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  7. bdb3011

    bdb3011 Junior Member

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    Do any of yo fine individuals have a link to a decent miniVC and techstream software? I've spent some time searching this site for info as well as Amazon and eBay for something to buy. The searches and options are more or less endless and I can figure out what's total crap or not? I'm hoping to run it on an old windows xp machine, but i'll get a more current cheap machine if needed.

    Thanks again!
     
  8. SFO

    SFO Senior Member

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    Kind of hit or miss at the lower price points ($15+), but mostly they work or will with the correct TS version. Find a seller with 'free returns' if worried about build quality. Some sellers will let you 'make an offer', just look at the sales history and see if lower offers were accepted and try to match.

    There are other cable options that cost more, like the 'VXdiag' ($50+), or even the Tactrix open port 2.0 cable for $170+ ( Tactrix ).

    Assuming you don't want to wait for a cable from China, here is a US shipper : Mini VCI J2534 16Pin OBD2 Diagnostic Cable For Toyota Lexus Scion TIS Techstream | eBay
     
  9. Skibob

    Skibob Senior Member

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  10. bdb3011

    bdb3011 Junior Member

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    Great info. Thank you!
     
  11. bdb3011

    bdb3011 Junior Member

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    Well, you guys were right. New accelerator position sensor in the form of a new pedal assembly and a shinny new throttle body (with new TPS on it as wall of course).... if any thing the problem is worse. Same codes on the fancy shop mechanics code reader. P0121 and P0122. No, I haven't put the techstream on her yet. That's next. I worry that maybe it's a short or a ground problem somewhere that will be next to impossible to find... or that the ECM is bad? Just at a loss here.

    Techstream here i come!
     
  12. dolj

    dolj Senior Member

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    It can only be plugs, connectors, wiring or the ECM itself, now.
     
  13. Skibob

    Skibob Senior Member

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    Have you tried @SFO ‘s troubleshooting links from post 4 yet?
     
  14. bdb3011

    bdb3011 Junior Member

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    To the best of my ability, yes. It doesn't exactly give much in the way of details. It basically comes to the same conclusion that dolj stated above: wiring or computer brain issue. Process of elimination also lends to those conclusions as well after the two parts i've replaced.

    I'm hoping to embark on the endless journey of trouble shooting the wiring tomorrow, starting with searching for grounding issues.

    Does anyone know what's entailed in replacing a ECM? And aren't there multiple ECM's in this car? :-/

    Thanks
     
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  15. ChapmanF

    ChapmanF Senior Member

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    Well, the really general term is ECU - electronic control unit. A Gen 2 has about a dozen of those (a Gen 3, north of two dozen). But only one of those ECUs is the one also called the ECM (engine control module).

    And as usual, as with any no-moving-parts, all-solid-state industrial-grade electronic controller, it is almost almost almost almost never going to turn out to be the problem. Wiring and connectors are going to be the usual suspects, as they have been all down the years.
     
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  16. bdb3011

    bdb3011 Junior Member

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    Can anyone tell me if techstream will do anything at all (more than a normal code reader) to help me track down the a shorted wire or ground problem?
     
  17. SFO

    SFO Senior Member

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    You will need Techstream, sooner or later.

    Do you have a multimeter?
     
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  18. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    It's not going to pop up and tell you "Wire #83 was eaten by a brown mouse on September 25, half a meter from the black 4-pin connector" or anything magical like that. Some detective work with a meter is still going to be required.
     
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  19. ChapmanF

    ChapmanF Senior Member

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    On the other hand, it will let you do things like watch, or record, the sensed values being seen at the ECU while you are out jiggling wires. So if you look at it as another tool rather than an oracle, it can be a pretty darn useful other tool.
     
  20. bdb3011

    bdb3011 Junior Member

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    The code reader i'm using now has the ability to watch the voltage to the TPS and accelerator position sensor live. Great idea to watch those values while wiggling and jiggling. Just need to decide what end to start from now... Seems like starting at the engine side of things and working toward the firewall might make sense? wish me luck!