Still P0401 after cleaning egr !! should we drive it?

The film is now about 10 times smaller - sorry, I didn't think about it right away

Here the link once again:
http://lares.nazwa.pl/Pliki/20220915_131113.mp4

Mat

 

Shouldn't it be possible for me to measure the voltage on the terminals with a plain voltmeter?
It should give me about 5 or 6 volts between a terminal and the ground, if the driver is trying to move the motor.

The peak seems to be somewhat under 40V and the stable voltage at the end of a pulse about 12V.

How do I connect a probe to a terminal in this plug? It seems to be sealed...

Mat

 

You use a thin type of test pin sold as a 'backprobe'. Careful to go outside the rubber terminal seal (which is crimped to the terminal):



If you look at the waveform diagram above, you can see a diagonal pattern where the peaks progress upward to the right, one horizontal division apart. At the same time, you can see a shallower diagonal pattern, where the peaks progress downward to the right, three horizontal divisions apart. That's how you know the valve is being driven to close.

When it is being driven to open, you'll recognize the complementary pattern: three divisions apart on the upward diagonal, one division apart on the downward.

You don't necessarily need to monitor all four channels to tell which way it's going; you can monitor two, as long as one of them is odd (EGR1 or EGR3) and one is even. It's the relative pulse timing that tells you the direction. You can't tell by monitoring two odds or two evens, because their pulses are always two divisions apart regardless of direction.

 

I have to use this car in few minutes, so I will see, what happens on cold start

You are writing, as I had a scope... but I don't.
I can backprobe it with a normal voltmeter, which should give me an idea, if the ECU is driving the motor or not.
I doubt if I can tell the direction with a voltmeter...

Mat

PS. And I'm really, really wondering, how I should get the probe in and get the fins of the sealing bent like in the illustration

 

Well, I'm writing to explain what the scope would be showing you, so that if you need to improvise some scopeless way to see it, you know what you're looking for.

It would be useful to know the direction though. Maybe you could breadboard up some little circuit that would show you the relative phase of two pulse trains.

You can take that up with Elektroingenieur; I think that's who made that drawing.

 

It looks like a Toyota drawing, I think.

Mat

 

Yeah, the forum software does that. If it sees something that looks like a URL, it tries to go fetch it (so it can do its thing where it builds a link based on the title of the target page). If your page includes something that looks like a URL but isn't fetchable (like a bare https://, for example), then when you try to save, you get the "Oops, something went wrong", one of history's least helpful error messages.

Maybe the same thing happens if the URL is for a video ... something that is fetchable, but isn't a web page with a title.

You can put URL-like stuff inside [plain] so the forum software won't try to follow it, but then it isn't a link the reader can click on, either. Or you can put it inside a [url] tag yourself, so you have control of how the link will look, and then the forum software doesn't try to generate its own.

You can do that even for an unfetchable URL (if you want): https://. (I had to use [plain] inside the [url] tag.)

 

I'm back from a short trip.
The car acts normally, no check engine light, no odd sounds.

I think, I have confirmed (with an improvised sort of stethoscope ), that the clicks at ICE shut down are coming from the EGR valve.

I would be much more relaxed if someone could listen to the EGR valve at the moment, the ICE is turning off, on another 2010 Prius and tell us if an "untouched" EGR valve clicks as well at this moment

Mat

 

After I thought about this clicks thoroughly, I came to some conclusion.

If this clicks mean simply, the computer wants to be sure, the EGR is closed after the ICE has shut down (it tries to go with the rotor to the dead end twice with a pause between the tries, in which time the rotor unspinns a little, so we can here two clicks and two unspinning noises), it could be a good diagnostic indicator to know, if the rotors ramp is in a good condition.

I can imagine, if the ramp begins to deteriorate, it will no more make this very clear clicks at the end of travel.

So - until now, I'm pretty sure, my rotors ramp is in good condition AND it clicks twice at ICE shut down.

Now, on the part of the PriusChat community, it would be to make sure that the clicks really do occur in every (or the vast majority of) working engines and EGR valves, and that with a faulty EGR valve ramp, there won't be that click, or you'll hear other sounds when the computer tries to close the EGR valve after the ICE is turned off.

Is my thought process reasonably consistent?

What do you think?

Mat

 

The thing that bothers me is the published waveform that indicates the rotor is always being driven against the stop whenever the engine is at idle, so there shouldn't be any further click possible at that point. Also, I don't know that it unspins much by itself, once the stator is fastened down. (It unspins while you're reassembling the valve, because then it can.) I suppose there could be enough mechanical play for it to unspin enough to make a click. Or the ECM could deliberately drive it a couple steps in the open direction, and then back. I'm not sure what the aim of that would be though.

It might stay mysterious until someone can actually capture a video that includes the clicks and scope traces of the driving signals at the same time. It might also be very interesting to see if the traces of the driving signals are different between the 34715200 and 34715700 firmware versions.

From the numbers you posted above, I'm guessing 34717200 is your ECM calibration, and clearly is different from any version we get in the US. i don't know if there was any service bulletin in your area, like the T-SB-0027-16 that we got, announcing an updated firmware, and so, if there was, I don't know whether your 34717200 represents the pre-update or post-update version.

 

I can understand your thoughts above.
As I understood the topic, the valve is driven close at normal working temperature, whenever the valve should be closed. Maybe it is not driven at all any more, if the engine shuts off - after this two tries to make sure, it is closed? If the engine starts again, it will be driven close again.

I'm simply sure, the clicks are there. Not sure thou, if it is the normal state (but the chance, it isn't, is very faint, I think).

I do not know if it is "unspinning" noise. I'v named it like this
And I'm pretty sure, you can assemble the valve without unspinning - you simply block the rotor with the stator as long as possible, and then the spring holds it without unspinning. Tried it several times with the old valve. However, I can not be absolutely, 100% sure, as the stator is not translucent

Yes, it would be the final proof for whatever it proofs for whatever software version

I'm sorry, I have done, what I could - my tools are limited.

The community here owns a lot of Priuses and, I'm sure, everyone can here to the clicks.

If the clicks are there in the majority of cars, we then should check the cars not clicking and determine, if they have the rotor ramp failing or a newer software installed or something else

I do not know this as well.
The TSBs are simple to find in the US.
In Europe it is more difficult, I think.
I do not know anything about any TSB in this regard in Europe.
I brought the old valve to my Toyota dealer and gave them the TSB, I found for the US...
Maybe they found something similar for Europe in their system - I don't know.
And remember - I do not own this old Prius any more. I'm driving another one

Mat

 

It seemed to me the prices were a little more reasonable at toyota-tech.eu than at techinfo.toyota.com, or at least the EU version had a cheap hourly rate available, where the shortest available in the US is for two days. So looking for TSBs probably only takes a few €.

I am surprised that some electronics hobby/kit supplier, like sparkfun, doesn't just have a little generic stepper motor step counter that you could backprobe into the terminals and would show the stepping direction and keep a count of steps. Such a thing could probably be built for a few euro in parts.

The nearest I came in a brief search was this reference to a free logic analyzer software that can do stepper motor decoding given < 10 € of hardware (at least, as of the post a couple years ago).

 

Hmmm... You are probably right. I even didn't think about looking by Toyota itself
My opinion is, the TSBs should be free accessible for anyone at no cost... Maybe without a detailed repair methodology, but the core information should be there.

One could do that of course, but even If I do that, we have actually no information gained - it is one case with a valve, that was disassembled... We need an easy method to gain more information from others.

I would propose to make a survey - listen, if you here clicks or not, give us the calibrations, eventually check your valve, if you have no clicks, but this after gathering more info about the coincidence clicks-calibrtations-modelyear.

Mat

 

In the US, you can find TSBs for free because a federal agency, NHTSA, requires the manufacturers to report them, and NHTSA's website has them available for free so you don't have to go through the manufacturers. That's a fairly recent development, though, following a law passed in 2012, and not immediately complied with even then. Also, in the US, it could probably be denounced as big-government tyranny at any moment, and discontinued, to make sure citizens remain free to pay the manufacturers for them.

Maybe the EU has some similar tyrannical agency where the TSBs could be found?

 

I would not name it tyranny

I like to have information on a _thing_ I have payed for. I like to have the possibility to repair it myself, or by anyone, I trust.

And yes, there is a institution in Europe:
Safety Gate: the EU rapid alert system for dangerous non-food products

Mat

PS. What do you think about a survey, I mentioned? Do you know how to ask for something like this?

 

Does Safety Gate have TSBs also, or only things considered to report "unsafe" conditions, like recalls?

 

I donn't tink, they have the TSBs...

Make a search:
"Toyota"
Product category: Motor vehicles

Search between 2010 and 2015 and you will see what they have.

Mat

 

Yesterday I had the possibility to hear to the EGR valve on an another Prius 2010.

It definitely clicks too, very similar to mine, but maybe not so clear.

If I can convince the owner of this Prius to let me open his valve, maybe I can make some photographs of the rotor, but it will not be easy to convince him

Mat

 

Maybe eBay could help with convincing him.