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2010 Gen3/Loss of Regen, ABS, etc.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Canard, Jun 20, 2022.

  1. Canard

    Canard Member

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    Hi all,

    2010 Gen3, ~350k km. Not a single issue to date, car has been bulletproof.

    Of course it happens out in the middle of nowhere on vacation... hit a big bump/broken pavement in a rough road at 80 km/h, and right after that the following symptoms present:

    -Loss of regen during braking (friction brakes only)
    -Traction Control warning light ON
    -((ABS)) warning light ON
    -((!)) warning light ON
    -((!)) warning light ON

    I am thinking that I've somehow either damaged or dislodged a wheel tachometer sensor ("ABS Sensor") - either the sensor itself or one of the wires/connectors somewhere. Since regen is gone I strongly suspect it's one of the front two wheels and not the rear - the front two sensors are required as inputs for a function of regen since the MG1/MG2 set are on the opposite side of the diff to the wheels. If it was a rear wheel sensor, I can believe ABS would be lost but regen should still function fine.

    I pulled both wheels off and checked the wires to the sensors - while fragile in their exposure, they both (visually) appeared fine. No damage that I could see. I was hoping that a connector had simply dislodged or something like that and I could press it back in place, but from what I can tell they come directly out of a sensor and then disappear into the panels around the wheel via a rubber grommet, and where they go from there I have no idea.

    I do not have tools to pull the terminal off the 12V accessory battery to try and clear/reset the ECU.

    I have a Scangauge II with me as part of my kit and I checked but there are no stored Error Codes - which I find kind of bizarre.

    One other minor thing I've noticed... typically, when I approach the car and open the driver's door, I can immediately hear the brake booster motor run for... maybe 5 seconds, before I even push the power button to turn on the car. It's not doing that but now I'm thinking that's because I typically drive VERY regen heavy, and maybe at the end of my previous driving cycle, the brake booster is "empty" so when I next re-start the car the first thing it does is re-charge it... but now that regen is not working, the brake booster is fully charged so there is no need for a long re-charge cycle.

    I am thinking based on my diagnosis I am safe to proceed home (carefully) as I am fairly certain it is not a more serious issue (i.e., punctured brake line, broken brake booster, etc.) but would love to know if anyone has had a similar issue and if there is an easy fix.

    Thanks in advance,

    -Canard
     
    offib likes this.
  2. Eddie25

    Eddie25 Active Member

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    Had the exact same issue and it was because the wheel speed sensor wire was barely routed wrong after I re-installed the wheel well splash guard. It goes above the splash guard and down to the wheel. I routed it correctly and haven't had a problem for 2+ years. Those sensor connectors must be extremely sensitive or something, this issue seems to pop up fairly regularly after people hit potholes, or mess around near the wheel well area. I'm not saying that's definitely it, but I'd move the sensor wire around on the side you hit bump on and see if the light goes off.
     
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  3. ChapmanF

    ChapmanF Senior Member

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    Because the brake system is able to blink out its trouble codes on the dash warning lights when you trigger it to do so with a short jumper wire, that's the first thing to try whenever you get bizarre results with some scan tool not seeing the codes. Scan tools not seeing codes are a recurrent nuisance around here, and the blink-code method neatly sidesteps that whole can of worms.

    You can search up other posts with the details on how to do that.
     
  4. Canard

    Canard Member

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    Thank you for the reply!

    Is the connector you're talking about "exposed" when I take off the wheel? I don't know the terms but there's an "inside" and an "outside" to the paneling that goes around the wheel... I don't know how to remove that or see the other side. When I took the wheel off, I could see that the wire appeard to have a nice clean loop (permitting the wheel to move up and down over bumps) and nothing looked tight, strained or damaged. I didn't see a connector at the sensor itself, it looked like the wire was moulded directly into the sensor... What is it you think I should move around?

    Can you give me some detail on what I should search for for this? I can't seem to find anything (but I'm probably using the wrong terms)... I don't have any wire with me either though, and am very, very remote (although no so remote I'm without signal :p)... so even if I did find it I doubt I would be able to scrounge up more than a paperclip...
     
  5. Eddie25

    Eddie25 Active Member

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    At 2:08 you can see him reach around the splash guard to disconnect a wire connector. I think that's the connection point that provides a lot of problems for people.

    You don't have to do any of the previous work or even disconnect the connector, see if you can just get your arm up there and fiddle with the connection/wire to see if anything changes. Like I said, I just barely moved mine and it's been fine for years.
     
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  6. ChapmanF

    ChapmanF Senior Member

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    Something like blink code jumper tc cg

    ought to do the trick.
     
  7. Eddie25

    Eddie25 Active Member

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  8. Canard

    Canard Member

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    Just confirming - that's the OBD port? Before I start sticking paperclips in things and really stranding myself :)
     
  9. Canard

    Canard Member

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    So, in light of reading about the dangers of inserting jumpers into the OBD port pins... I pulled all the wheels off once more and reached as far behind the plastic panels as I could to jiggle the connectors... no avail. :(

    I've found a dealership 45 minutes away and will see if I can get them to have a look in the morning.
     
  10. ChapmanF

    ChapmanF Senior Member

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    It might be good to say where you were reading about such "dangers" of using the diagnostic code blink-out feature of the car for the exact purpose it was put there for.

    Here on PriusChat we did have one kind of ur-thread back in 2009 where a bunch of somewhat spurious claims about those "dangers" were spread across a bunch of posts all made by one single member, and another thread where somebody made a post in 2017 that just copy-pasted the word-for-word claims from the 2009 one.

    As one example, that 2009 thread included these claims:

    Toyota manuals sometimes mention SSTs (special service tools), and the PriusChat member who posted that seems to have thought the SST in question is somehow "goof proof" and not just a wire.

    That's actually funny, because every place in the manual that tells you how to read codes with it will give you the order number of that SST, and it's (wait for it) a wire.

    [​IMG]

    It does have crimped-on pokey ends that fit the terminals perfectly, and that makes it a little better than a random wire, and even more better than a paper clip. Also, it has three ends, making it usable for those very few without-Techstream procedures where you jumper three terminals and not just two.

    But there's nothing remotely "goof proof" about it. Anybody who can't count to pins 4 and 13, or find them in the drawing as shown above, should not be issued one. But Toyota is pretty sure both of those abilities are in your skill set.

    There is a nice thing about knowing that SST part number: it's a great thing to search on in a PDF of the repair manual, if you want to find all the places where there are non-Techstream ways of doing something.

    That way, you can also check how easy it is to find any place in the manual that "*strongly* cautions about using the "blink" method." Good luck with that.

    In a few places, you might find a mild "NOTICE:" (embedded in the instructions that are telling you how to use the blink method!) saying something like "Connect the terminals to the correct positions to avoid a malfunction."

    Yes, well, yes, can't argue with that advice.

    As I posted on that 2009 thread back in the day:

    It's too bad we still have people's searches landing on old threads like that, because when somebody's car doesn't work, it doesn't do them any favors to rehash old scaremongering posts to discourage them from using the exact feature the car was built with to let them get the trouble code.

    (Then, of course, there are the other threads people keep landing on where the jumper procedure is only described for clearing codes, and not for learning what the codes are. That's also funny, because the lights blinking the codes out is the first thing that starts happening when you power up with the jumper ... when people follow a procedure that just skips ahead to clearing, they have to actively ignore the car telling them what the issue is.)

    By the way, if you really do want a "goof proof SST" that you can use to jump the right pins without having to count them, you can always buy a J1962 connector and a couple switches, and build one. I'll confess I built one for me:

    [​IMG]

    But nope, nothing "goof proof" about Toyota's pokey wire. Just count to the right pins. All there is to it.
     
    #10 ChapmanF, Jun 20, 2022
    Last edited: Jun 20, 2022
  11. Canard

    Canard Member

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    I am very sorry, I didn't mean to cause any offence and am going with limited knowledge and am in (what is to me) a very stressful situation, trying to make the best decisions I can. We're 3000 km from home in a remote mountain area and the last thing I want to do is lose any kind of functionality with my brakes.

    I'm fairly technical so appreciate all of what you are saying but admittedly check this forum very rarely specifically because the car has been so reliable. So I am not up to speed on this or the history of the messaging. The first post that came up in my searching was basically verbatim the one you mentioned.

    I very much appreciate your reply and thanks for the additional information!

    Can you confirm that the view in the diagram is showing the view of the car-side of the connector? i.e. I should be connecting these two pins?

    upload_2022-6-21_6-55-7.png

    Where can I get a list of what the blink codes will mean, if I'm able to find something to jumper the pins? I found the attached .PDF, but from what I'm reading, I'm going to get out a two-digit code but the codes in this document seem more complicated than that. Or is it just the last two digits after the "/", i.e., 31, 32, 33, 34, etc...?

    -Canard
     

    Attached Files:

    #11 Canard, Jun 21, 2022
    Last edited: Jun 21, 2022
  12. Canard

    Canard Member

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    Perhaps not the most elegant solution but I managed to jam some tweezers in the correct pin sockets of the OBD port:

    upload_2022-6-21_9-41-39.png

    In doing so I got the following codes:

    upload_2022-6-21_9-2-15.png --> Code 43

    upload_2022-6-21_9-2-56.png --> Code 34

    upload_2022-6-21_9-3-15.png --> Code 36

    Also while driving for ~10 minutes, twice, the lights all extinguished and regen returned to normal, and then a minute later they all came back again, with loss of regen. I am thinking this is a loose connection to one of the wheel encoders/tacho/ABS sensors. Would you agree?
     
    #12 Canard, Jun 21, 2022
    Last edited: Jun 21, 2022
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    Have dealership do a quick diagnostic?
     
  14. ChapmanF

    ChapmanF Senior Member

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    Good work! I've replaced your light images with what we normally call those lights: VSC (vehicle stability control), ABS, and ECB (electronically controlled braking).

    Where you find the goods on the codes is in the repair manual. The codes you would see on a scan tool are these five-character things where the first character is one of P, C, B, or U, the next can only be 0, 1, 2, or 3, and the next three can be 0 through 9 or A through F. In the manual, those are listed next to the two-digit blink codes, separated by a slash, like C0215/34, for example.

    Regrettably, you can't just assume anything simple, like the blink code being the last two digits of the DTC or anything tidy like that. (I think the codes for the heater do all work that way, but that's kind of the exception.) So you just have to look it up.

    Because of the way the two codes are listed with a slash between, there's a pretty easy search shortcut if you have a PDF of the manual to search in. You just search for the blink code with a slash in front, like /34. Leave off the slash and you'd get every place in the manual there's a number 34 for any reason, but /34 will often take you right to the code.

    There are three separate tables in the manual, giving the ABS codes, the VSC codes, and the ECB codes. Some of the blink codes overlap, so once search takes you to a code, scroll up to the top of the table it's in to make sure you got the right one for the light that was blinking. 34 on the ABS light is C0215, an issue with the left-hand rear speed sensor signal. (If your search had landed first on /34 in the VSC table, you'd think it was C1234, a yaw sensor issue, and you'd be off on the wrong track. Same if you landed in the ECB table and thought it was C1228 about the STR solenoid.)

    Your VSC 43 and ECB 36 both just mean "hey, go look at the ABS code." The search-with-a-slash trick doesn't find those because they don't themselves correspond to any DTC, so they appear in the table without slashes, up at the tops of their respective tables.

    So the C0215/34 is the real issue you've got. The thirteen-page section for that code in the repair manual describes what the speed sensor signals look like, and how to troubleshoot why the ECU might not be getting a good signal from that sensor (which could be an issue with the sensor itself, but also with the wiring or connectors).

    That code also comes with an "INF" subcode that can give you a little more detail about the rear left sensor issue. There are seven possible INF codes for this one, 531, 532, 533, 534, 536 (caught you napping!), 537, or 538. So if you had 538, say, you would know that the sensor voltage had dropped for at least a half-second during a time when the IG1 voltage was 9.5 V or above.

    But you can't get the INF codes by light blinks; you do need a scan tool for those. But with the light blinks you now already have the basic C0215 code, so you've confirmed you're looking at a left rear speed sensor issue.
     
    #14 ChapmanF, Jun 21, 2022
    Last edited: Jun 21, 2022
  15. Canard

    Canard Member

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    Presumably, it could also be an issue with the toothed ring on the hub itself which generates the signals that the sensor picks up. On my smart fortwo cdi, they call this a "reluctor ring" and they were notorious for rusting and then splitting, giving a "dirty" impulse stream to the sensor, which the car's ECU could not properly interpret and thus would throw an ESP light up, and disable every electronically controlled braking function... sound familiar? :)

    Out of curiosity, where does the cable from the rear speed sensor disappear to, behind this rubber grommet?

    upload_2022-6-21_16-26-37.png

    upload_2022-6-21_16-29-33.png

    At the front wheels, I could feel where the connector was behind the splash guards. But at the rear, it seems to go directly into the frame somewhere. I am picturing there must be another connection point behind here?

    -Canard
     
  16. ChapmanF

    ChapmanF Senior Member

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  17. Canard

    Canard Member

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    Made it back home - 2 weeks and 6500 km later. The problem is now intermittent and comes and goes. Not surprising I suppose, if it's a loose wire... have had 3 days in a row now with the problem not reoccurring. One or two times when pushing the brake pedal, there was a lot of clicking and whirring down by my feet - sounds I've never heard before (and I'm very familiar with the motor-whine noise that often occurs down there - it wasn't that).

    Out of curiosity I measured the voltage of the 12V accessory battery.

    Car off: 12.0 V
    Car on: 14.1 V

    Is this within an acceptable range? I read in one thread that anything under 12.4 is sus. Took delivery 2010; battery has only ever been replaced once, in early 2018, so it's about 4.5 years old.
     
    #17 Canard, Jun 29, 2022
    Last edited: Jun 29, 2022
  18. ChapmanF

    ChapmanF Senior Member

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    Depends on why you're asking the question. If you're asking to stay on top of the condition of your battery, under 12.4 may tell you it's not getting quite fully charged, or it's no longer in the greatest condition and you could start saving money for a new one.

    On the other hand, if you're asking "could 12.0 volts when off be the secret reason why there is a trouble code for the left rear speed sensor signal?", that would be a no.
     
  19. Canard

    Canard Member

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    I am asking because I wondered if a low voltage might cause other errors to crop up (like the issue described in the previous posts). You obviously know much more than I do, so I am asking you that question.