Gen4 no power- how can you put in neutral?

That's fine; the documentation from when I conducted that experiment is what you saw me post in February (linked upthread), which either is or isn't enough to satisfy you, and if it isn't, well, that's exactly why experiment results get reported along with the step-by-step of how anyone else can reproduce the experiment.

There are some experiments that take a lot of time or prep or special equipment to conduct; this one is dead easy. Matter of minutes. The connector A23 mentioned in my instructions is correct for gen 3 (accessed by easy removal of the glove box); anyone reproducing the experiment in a different generation will need to spend a moment with the wiring diagram to find the corresponding connector for their generation, and that'll be the hardest part of the whole thing.

The main reason we haven't seen some other PriusChat members already reproduce it might be that they haven't seen a need, not generally suspecting me of faking experiment results. But if you do, that's totally fine; the whole point of including the repro instructions with the results is to make it clear that anyone wishing to check my work for any reason is cheerfully invited to do so.

Under the circumstances, I'd be happy if a few more members felt like reproducing it and reporting their own results. That still may not satisfy you personally, given your past history of even rejecting independent, corroborating reports from multiple members on another topic. Nevertheless, it would be of service to others reading this thread, who right now have little more to go on than whether they think you or I sound more convincing.



Edit: strictly speaking, the experiment that I reported in February involved first unplugging the Park actuator and then powering off the car while already rolling (long-pressing the power button to force off).

I spoke upthread of another approach, unplugging the Park actuator and then immediately powering the car off while stationary, then just rolling the powered-off car. I did it that way, too, around the same time in February, but might not have reported it then. Anyone wanting to reproduce the experiment could use either approach, or both.

If you start with the car stationary and powered off in neutral, and then push to get it rolling, you'll notice your first push has to be a little extra hard. As outlined upthread in post #12, you could use the length and force of that extra starting push as a rough way to estimate the value of the capacitor circled in green.



Doing that (and then comparing the estimate to the cap's labeled value) would be a fun addition to the experiment, which I might return to someday, time permitting.

 

It's just not worth it.
Seeya.

 

The well-prepared tow driver usually shows up with options in case a car can't be gotten out of Park.

 

That might allow the shifter to go into neutral, but the car will not safely coast in neutral.
The car can be towed for short distances at low speed when the car is in READY mode and operating normally.
The approved way to tow a Prius is either on a flatbed or with dollies under the drive wheels.

 

Towing with all wheels on the ground falls under the "Emergency towing procedure" in the owners' manual. That can be found on page 666 of a US 2022 (gen 4) owners' manual, or page 552 of a US 2023 (gen 5) manual, and presumably nearby in other editions.

For both gen 4 and gen 5, the recommendation is for short distances and speeds under 18 mph (30 km/h).

Both versions instruct you to "start the hybrid system" (go READY) if the car will, or if it won't, to go to IG-ON instead (two power-button pushes, no foot on brake). (As already covered in this thread, you need to get at least to IG-ON for the parking pawl to retract.)

Both versions explain that if you tow in IG-ON rather than READY, you'll be doing without braking and steering assist. As for how easily the car can be pulled or pushed, there is no difference, as there is no need to have the hybrid system on for the car to roll in neutral.

If there's any doubt about the 12-volt battery supplying IG-ON power for the full length of your tow (or, say, you have only used a small jump pack to get to IG-ON long enough to retract the parking pawl), unplugging the connector to the parking pawl motor after shifting to neutral will allow powering off without returning to Park. The car rolls just the same.

I made some distinctions between gen 4 and gen 5 in this post because there are some differences in how the transmissions are lubricated. I'm relying on KMO's post here for those details.

From KMO's notes, gen 4 Prime includes an electric oil pump for use in long stretches of EV driving. If there is no power, of course that pump will not run. Gen 4 still does have sling lubrication also, like the earlier gens, so oil will be circulated that way in any case.

Gen 5 apparently has no more sling lubrication, but adds a mechanical oil pump driven by the output (which will therefore be pumping when the car is towed, power or not). KMO notes there are some control valves that select between the input-driven or the output-driven pump, but the notes don't say if those valves are electrically operated, or which selection is their rest position without power.

With either design, the lubrication is probably going to be adequate for the short distances and low speeds that the manual recommends.

 

I'm skeptical that you were able to disable the parking lock while the car was off.
When I asked for evidence, you deflected.

 

So you are skeptical of a claim made by whom? Are you saying that I have ever claimed I disabled the parking lock while the car was off? If so, please link to any post where I claimed that.

Please identify (a) the post in which you asked me for evidence of that, and (b) the post in which I deflected. Please be specific.


Are you perhaps thinking of the posts where I have described shifting out of Park while the car is ON, then unplugging the Park actuator motor, then turning the car OFF, leaving the car not in Park? Yes, I have done that, and made posts explaining how to do it. It is easy to do.

 

Here is why the freewheeling explanation doesn't add up:
First of all, the car must be running, in READY mode, for the parking pawl to be unlocked.
There are a number of scenarios where freewheeling will not achieve a torque-free "neutral."

• Electric motor running (gasoline engine off).
• Gasoline engine running (electric motor off).
• Both power sources running.
• Car moving at any speed.

In each of these cases, the computer must provide some control over each power source to achieve a zero-torque condition to the wheels. Otherwise, the motion coming from the wheels will force one or both power sources to turn.

So the question remains; "In what scenario would the 'neutral' simply free-wheel the electric motor?"

 

In post #28 you've written you were skeptical about whether I was able "to disable the parking lock while the car was off" and in #29 I asked you to link to any post in which I ever claimed that.

Also in #28 you say that you asked me for evidence of that and that I deflected when you did, and in #29 I asked you to identify specific posts where that happened.

As you have neither done so nor retracted #28 I am asking again. Your post #30 is non-responsive.

 

I remain skeptical, is as my right.
That's not the same as claiming you are a liar.

 

I thank you for not claiming I am a liar. Nonetheless you have still not supplied specifics or retractions for what you did claim in #28 and for which I requested specifics in #29. Please make your choice, with clarity and specifics.

You did speak in #28 of a claim to be "able to disable the parking lock while the car was off". Are you saying that I ever made such a claim, or not? If you are saying that I did, please link to a post where I did.

You did say in #28 that you asked me for evidence of that, and that I deflected. If you are still saying that, please link to both of those posts.

 

I regret I ever engaged you on this topic. Let's drop it.

 

The easy answer to getting a Prius on a tow truck with the Parking pawl engaged AND the car is only accessible from the back is to simply drag the car a few feet. Tow truck drivers do this all the time. It will not damage the transaxle.

Normally they would jack up the front and place dollies under the wheels and simply push it out.

Actually a No Ready with poor tow truck access happened to me. In my case power on (not Ready) still allowed neutral and the car was simply pushed out.

If one wishes to truly understand how the hybrid transaxle works, he should spend some quality time watching Weber State University classes on the subject as captured on Youtube.

Like any college curriculum, the student has to start with early Toyota hybrid theory videos and progress through to detailed transaxle design. They use actual vehicles and do complete transaxle explanations and teardowns.

The professor does not repeat detail as subsequent classes progress which means the student has to absorb the earlier training. Toyota endorses this training and provides access to information making this a good resource.

 

John Kelly does a great job of explaining how a Prius works. Unfortunately some of his videos are over 20 years old.

 

As I said if you want understanding of Toyota's groundbreaking transaxle you start at the beginning.

 

Man-o-man, OP and tow truck long since come an' gone, and both you guys still duking it out.

 

Replying in this thread because at least it's about neutral, unlike the hijacked one which was about the Car Scanner app. Taking the most TL;DR part first:

Again, it would only take you one time rolling a Prius in neutral with all power cut (look ma, no computer monitoring anything!) to recognize that your version of common sense has a gap somewhere. It seems you still haven't tried that, while spending the better part of a year spreading this "common sense" into one thread after another.

On to details:

You can look the gearing up; for a gen 5 PHEV you can find the ratios here. They tell you that MG2 hits 10k RPM at 107 km/h road speed, and MG1 will be doing about −7850 RPM at that time if the engine is stopped. (You can see these numbers on, yes, Car Scanner, or any other app that displays the live data.)

Rare earth magnets make engineers smile because they can be quite small and light for a given magnetic field strength. They don't however, make any different kind of magnetic field than any other permanent magnet, or change the physics of a spinning generator.

From physics you find that as you spin the permanent-magnet rotor, a voltage is always developed in the stator windings. A voltage by itself, however, isn't power. Power is voltage ✕ current, so when zero current flows (as when there is no electrical load being fed by the generator), there is zero power involved, no matter what the voltage: anything times zero is zero.

As you apply any electrical load to the generator, and as you let the load current increase, the MG gets harder and harder to turn. The voltage times a nonzero current is nonzero power now, and you need as much power to spin that shaft as there is electrical power being generated.

That is why, when you regen brake a Prius and the car accepts perhaps 20 or 30 kilowatts of generated power, the MG is so difficult to turn that it slows the car violently.

That's also why, when you are not regen braking, or when you are in neutral and there is zero electrical power to or from the MGs, the MGs are an insignificant resistance to the rolling car. 7850 or 10k RPM for a well-lubricated shaft in good bearings is no big deal, and that's the whole scene when there's no electrical work for the magnets to be doing.

This often doesn't seem like common sense until the first time you actually have a small generator in your hand and try spinning it, first with no electrical load attached, and then with different amounts of electrical load. That's an experience many of us got to have in high-school physics if not before, and it makes you go "oh!", and what you learn at that moment becomes your new, better-informed common sense.

This fact about how the resistance to turning a generator depends on the electrical load applied is getting repetitive, as you already saw it back in February from me and from KMO (who also has had enlightening hands-on experience spinning a generator with different loads attached).

But of course it's repetitive; it could hardly be otherwise when you keep looking for new threads to repeat months-old misconceptions in, where people won't see the prior discussion.