2010 Gen3/Loss of Regen, ABS, etc.

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.

 

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.

 

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.

 

Something like blink code jumper tc cg

ought to do the trick.

 

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.



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:



But nope, nothing "goof proof" about Toyota's pokey wire. Just count to the right pins. All there is to it.

 

Have dealership do a quick diagnostic?

 

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.

 

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.