Water Pump

@chap

Responding to the last block of text you wrote, and it is funny because it is exactly what you are doing in this thread.

You seem to think the J0V is only for the the inverter failure but it is really just a safety switch in the computer.

I really really hope this is the last time I have to explain anything to you regarding this issue.

If you have never had the P261B code then you really should not even be responding here period.

Posted via the PriusChat mobile app.

 

One of us is contradicting everything that is perfectly available for you to learn about what J0V is, and it ain't me.

We can worry about that if we ever get to the first time you're explaining something to me about it, rather than making a show of your lack of interest in getting the basics straight.

But we've come a little far from the original poster's question, which was a simple one:

Now that is a good question. And the answer to the OP's question might be that there may be no trouble code programmed in for an overspeeding water pump.

There's P261B. That's for when the water pump is revving too slow (ECM is sending it a duty cycle >= 40% but the pump turns below 900 rpm).

There are P261C and P261D, but those are electrical checks on the pump rpm feedback circuit (voltage too low or shorted to ground, or too high or shorted to +12, respectively).

At least as of 2010, there isn't a code defined for the pump going too fast.

But look at a way these pumps fail:



Impeller breaks apart.

Without the structure of the impeller to move the water, the pump more or less free-spins and may end up hitting nearly double the target rpm:



without really moving the water. But there's no trouble code defined that catches that case.

As far as the question from the original post on this thread, probably nothing more than that was needed to answer it.

 

This "overclocked" water pump wouldn't happen if it was belt driven. It's too easy for new-and-innovative to backfire.

 

So from what I'm reading so far and understand, it's a 'no there is no CEL for a bad water pump' and it should be replaced every 100k. That is MY understanding.

 

Well, it doesn't fail because it's 'overclocked' ... it overrevs because it already failed. The plastic impeller breaks, so it isn't doing the work of moving water, so under the same motor torque, it just spins way fast.

If a belt-driven pump had a similar plastic impeller that broke apart in a similar way, well, it wouldn't rev faster because it would still be locked to the belt speed. But it still wouldn't be moving water. And you'd still have no way to know till you caught the temp going up.

The design of the two-piece plastic impeller seems to be the 'oops' part, and the way that top bell of it is affixed to the blades. And the lack of a temp gauge on the dash. And the lack of a trouble code for "hey, spinning too fast, did your impeller break off?" At first they probably never thought "runs too fast" was on the list of problems worth checking for.

I wonder if in any later year they added a check for "too fast". I have a hazy memory of hearing of such a code, but in a 2010 manual I definitely don't find one. In principle that does give you a way to detect it, an advantage over the belt drive (assuming a similar bustable impeller).

I pretty much have coolant temp shown on the ScanGauge at all times anyway. I might start looking at it more often.

I can also imagine now and then doing the pump test in Techstream and comparing the target and actual speeds.

Right-ish. There will be a CEL for some ways the pump can fail: if it's tired or binding and goes too slow (P261B), or if there's a problem with its wiring (P261C or D). However, at least for some years, there won't be a code for if it loses its impeller and runs too fast, and that is one of the ways it can fail.

 

@AzusaPrius
"I really really hope this is the last time I have to explain anything to you regarding this issue."

HAH! YOU SO FUNNY!!!

 

They did, according to the Repair Manual series (more info) for 2011 and later: diagnostic trouble code P148F, Engine Coolant Pump Over Revolution. The Diagnostic Trouble Code Chart page says the the MIL “Does not come on” for that code, however.

 

Well isn't that handy!? Once your engine overheats you can check the stored codes and see why.

@Elektroingenieur, do you see any published threshold for an overheat warning or shutdown in the absence of a water pump DTC?

The 105℃ threshold that I quoted



is only shown as a fail-safe action when P261{B,C,D} is present. As an experiment, I ran mine up to that temperature but with no water pump code (by disabling the radiator fans instead), and what happened was ... nothing. No warning light, no message on the MID, no shutdown of any kind. I assume there must be a higher threshold where some warning or action is produced even without a known water pump problem, but I don't really want to just push the temperature till I find it. I chickened out at 107℃.

I would like to see what really happens at 105℃ with a water pump code, but I don't really want to disable the water pump to do it. Exposing the engine to local hotspots with non-circulating water is a bit further than I'd like to go in the name of science.

Hmm, maybe leave the water pump running, use a function generator to fake a sub-900 rpm feedback signal, make a P261B that way....

 

Short, chauvinistic approach, just change the dang thing at 100K miles. And pray.

There's another active thread going, same thing.

 

Maybe if I throw this in and it is not coming from me directly it would be believable. I just found this info have no idea how it is not found out about sooner by anyone else, yet I need this to help people believe me and not waste their time or lose their lives in an accident.

Any motorhead knows this guy: 2010 Toyota Prius turned off | Bob Is The Oil Guy
Posted the year I got the J0V update early in the year.

Very recent post online: If your vehicle overheats - Toyota Prius 2010 Manual

I couldnt help but try and search for something that is like my experience after seeing @chapman edit his last post multiple times and go into a frenzy.

 

Doesn't seem like anybody ever disputed that engines can overheat. Or that warnings might be given when engines overheat. Or that ECUs might stop engines when they overheat.

I half expected you would have supplied links that would somehow support your strange linkage of engine overheating to firmware concerned with transistors in the inverter. But neither a blog post with owner's manual language describing what to do when a car overheats, nor a discussion between BITOG forum members trading ideas why an engine overheated and shut down, comes anywhere near carrying that load.

But of course you've got me with the timing here:

If a guy posts in BITOG's forum on "May 9, 2018" that a friend's Prius overheated and shutdown, and seven months later on December 20, 2018 the J0V firmware update was announced, with owner notification to begin "in mid-January 2019", well, I guess I've got to hand it to you. You've proved that guy's overheating Prius shut off because of that firmware update. I must acknowledge greatness when I see it.

To say nothing of your having "got the J0V update early in the year" ... months before even the filing of the defect information report that led to the J0V recall. A VIP customer, for sure. That's some real clout.

Edit: here goes another frenzy of one edit. Just looked a little unfestive without the screenshot.


2nd frenzied edit: replaced 'bare' with 'unfestive'.

3rd frenzied edit: maybe worth saving the original links from #30 just for clarity.

 

I actually double checked when I got the J0V update and it was 1/8/19



Posted via the PriusChat mobile app.

 

Clear, then. One of the first to have the J0V update done (as it was first announced in December 2018 and only starting to roll out in January 2019), and almost to the day eight months after the overheat shutdown reported in the Bob Is The Oil Guy forum from May 9, 2018.

 

I know what you are thinking chap and let me tell you that I do not know that person or friends of them. They state their mileage and mine is way below that so no dice on that.

Also I was already getting the P261B code before the J0V update and guess what?

The car drove on that very same hybrid pack, like it is supposed to if your battery is good enough. Up until the day I replaced a module and the waterpump after the comlplete shut down. With the codes I said I had, so if the recall was to prevent that from actually happening, it still happens.

If you want I can sell you my OEM warerpump that gave me the code P261B you pay for S&H no tax.

Then you will see that your car if it has the J0V update will shut down if it has a weak battery and bad waterpump.

Loss of all power to ABS, power steering and engine & electric power.

Meaning coast to side if you have a chance and tow or reset codes and see what happens.

Posted via the PriusChat mobile app.

 

When I have the time I will check that, because I'm curious. I won't need your water pump because I will spoof the WPI signal to generate a P261B condition without really stopping the coolant circulation. There is no need to actually abuse the engine just to gather data. It may be after the holidays before I have the time and materials together to do that.

After finding out what my car does (which has the J0V update), the obvious next thing to check would be what happens in a car where that update has not been applied. That was going to be a bit of a challenge, but you solved it already when you supplied a link showing somebody's car shut down on the freeway eight months before the J0V update existed.

 

Little bit of progress. There's a pair of control/feedback signals between the ECM and water pump, WPO and WPI. The ECM sends a pulse train to the pump on WPO, where the pulse duty cycle indicates the desired speed. The pump sends a tachometer signal back to the ECM on WPI, where the frequency of the signal indicates the actual pump RPM.

The manual does show sample waveforms for WPO and WPI:



However, the "HINT" for WPO seems to be a mistake in translation. If the WPO wavelength changed with pump speed, that would mean the ECM isn't just modulating the pulse width, but also the frequency, maybe having to synchronize it with the pump. That's not unthinkable (after all, the big MGs are driven that way), but it would make building a spoofer circuit more fiddly. Happily, the manual's just wrong about that part; as the scope shows below, the ECM generates WPO at what looks like a fixed 25 Hz frequency, and only varies the duty cycle to convey the requested speed. That will be much more convenient.

The WPO and WPI signals can be accessed at the water pump connector or the ECM connector, of course, but the water pump connector's not so easy to reach and the ECM connector is dense and crowded, and they both have weatherproofing seals that make them harder to backprobe. It turns out the most convenient place to scope both signals is at connector DA2 inside the underhood fuse box.



Pin 10, blue, is WPO, and 11, green, is WPI.



Because this lives under the fuse box cover, no rubber terminal seals, just the place for some probes.



The Techstream active test for the water pump only gives two speed choices: off and 3000 rpm. I might have liked a few more choices just to be more sure how the proportions work out. But anyway, here's Techstream requesting 3000:



The request (WPO, the upper trace) is exactly 50% duty cycle, 25 Hz (those are 10 ms divisions). The tachometer feedback on the bottom seems to have a period around 9 ms, or about 111 Hz. If this is generated as two cycles per pump rev, that would be around 3300 pump rpm, which is roughly what Techstream was reporting.

With the active test disabled and just turning on the cabin heat, the car drove the pump like so:



The high part of the WPO cycle has dropped to about 40%, which you might guess to be a command for 2400 rpm, if 50% was 3000. And Techstream said the request was for 2475. The tachometer feedback now looks to have around an 11 ms period, roughly 91 Hz, or 2730-ish rpm if there are two cycles per rev. Techstream said 2725 actual speed, so that's probably the right story.

Both signals swing between +12 and ground.

For another day: to pop those two terminals out of that connector and intercept them, so I can send a spoofed WPO to the real water pump to keep it running at a reasonable speed, and send a spoofed tach return back to the ECM and lie about the pump speed to see how the ECM behaves.

 

Checking sloppily with a multimeter...

The ECM appears to sink current on WPO, as if the pump has a pullup and the ECM pulls it down.

The ECM appears to source current on WPI, as if it has a pullup and the pump pulls it down.

 

If that's the case, I like that design. The only way to have a signal at all is if the entire circuit is intact. So you can scope it anywhere.

Posted via the PriusChat mobile app.

 

Well, yesterday was a beautiful day for that. I popped the WPO and WPI terminals out of that connector DA2 (much easier after grabbing a cotter pin out of the junk drawer and Dremeling it to the exact measurements of the terminal release tool illustrated in the wiring diagram; usually I find a small screwdriver and the right amount of cussing will release many terminals, but this time not so much). In their place I inserted two new 82998-24350 repair wires, so I had separate access to both the WPO and WPI signals at the ECM and the original wires carrying them to/from the pump. The plan was to display, top to bottom:

• WPO - the pulse output from the ECM showing how fast it would like the pump to run
• SWP - the pulse train I'm actually sending the pump to tell it how fast to run
• NWP - the actual tachometer signal coming back from the pump showing how fast it's really running
• WPI - the signal I'm actually sending the ECM for the speed I want it to think the pump is running

For this photo, I had jumpers on a breadboard connecting WPO to SWP, and NWP to WPI, just like in the unmodified car, so of course they match.



Then for the fun part: to pull out those jumpers, so I could see the ECM's desired WPO pump speed signal but send something different to the pump, and see the pump's actual NWP tachometer signal but send something different to the ECM.

Cluttering the picture slightly, the function generators I'd use to spoof the SWP and WPI signals didn't have a zero-to-twelve-volt amplitude setting, so I needed to stick a couple transistors on a breadboard to use the function-generator outputs to pull down the pump and ECM inputs (which have their own pullups). That of course inverted them, so I had to keep reminding myself to set 70% duty cycle when I meant 30%, and so on.

Then, in order to see anything on the ECM WPO output and the pump NWP output, I needed to bring +12 over from the fusebox and supply pullup resistors for those. Ended up looking a little mad-scientisty for what's really a fairly straightforward test, but it was a gorgeous day to be outside.



The WPO and NWP signals look a little squashed because I used much higher resistance pullups than what the car uses (well, I had some 220 kΩ resistors right at hand). I didn't want to overload anything by guessing too low, and since those signals were just for me to look at anyway, there was no need to try to get closer. I can still see what they're doing even if they look like shark fins.

In the fusebox can (not) be seen the 30 amp - 30 amp - 50 amp triple fuse for the radiator and heater fans that I removed, so the engine would not be able to cool itself.

With those preparations out of the way, it was onward to the original question: what happens when the engine has a water pump code, and overheats?

The reader may recall that what the manual says happens is this:



if the manual is right, the engine should stop, while the car remains otherwise in READY state on traction battery power.

Alternatively, it has been claimed upthread that the whole car shuts down, dead without motive or steering power (much like the former issue with some inverter failures that was fixed in recall J0V).

So ... with the fan fuses pulled, and sending an actual reasonable water pump request to the pump so the engine is not really put in danger, but sending a different pump tachometer signal back to the ECM, confirming the check-engine light is ON and Techstream shows the pump code ...

it's just a matter of keeping a foot on the go pedal to hold the engine above idle and watch the Techstream data list to see the coolant temp going up and up and up and ...



Boom. Triangle light, "CHECK HYBRID SYSTEM", and the engine abruptly shuts right down. Car is otherwise still fully powered up and with the READY light on. (The CHECK HYBRID SYSTEM message didn't really look diagonal like that, of course; weird interaction between the MID refresh rate and my phone camera.)

The engine shutdown happened just an instant before Techstream showed the coolant temp as 221 ℉, but of course Techstream is just polling those values and is a moment behind reality. In Techstream's next redraw of the data list screen, that was exactly the temperature shown. In Celsius that's 105 ℃, just as the manual says.

My verdict: car did what the manual says, engine shuts down at 105 ℃, triangle, CHECK HYBRID SYSTEM, car is still powered and READY.

Other notes, while I had the stuff apart:

I believe the pump tachometer outputs two cycles per revolution, so you multiply the frequency in Hz by 30 to get rpm. The rpm shown in Techstream always is that value minus 25. Send the ECM 20 Hz, see 575 rpm. 30 Hz, 875 rpm. 200 Hz, 5975 rpm.

The ECM clamps the rpm value at 6375 rpm even if you send a faster tach signal than that. I wanted to see if it might wrap around (say, near 6553, anyone?) and possibly explain some reports of getting a pump underspeed code when the impeller has broken and you'd expect overspeed. But that isn't what happens.

The working range of duty cycles you can send to the pump is (roughly) 20% to 80%. Fed 80%, it does 4625 rpm (in my car, with coolant, non-busted impeller). Above 80% it doesn't go any faster.

Fed 25% duty, it does 1450 rpm. Fed 20% duty or less, it doesn't spin at all. I did not take time to try 21, 22, 23, 24 % just to see where exactly the threshold is.

Now to go back out and make the stored codes go away ....

 

@chapman

So the engine shut down huh?

I told you so...

Any high temp light?

I bet not...

So I can not remember if your prius has had the J0V recall done but isnt that supposed to prevent that from happening?

I guess not..

https://plugoutpower.com/

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