Car Scanner Pro app for Diagnostics

Part of the problem is individual pdfs don't provide all the information needed. Online the links work; in the pdf they don't. Wiring diagrams spred over many pages of a pdf don't make it easy to trace circuits and find parts locations which are in another pdf; online is easier. Theory of operation is another abbreviated document; the whole Toyota TIS scheme is setup for trained and experienced techs who don't need routine details. On top of that changes are not available in some early captures floating around the ether.

As a result many independent shops use alternate sources from places like Alldata. Which still charge.

 

A lot of what you'd want for theory-of-operation is covered in the New Car Features manual, which is also available on TIS, and is quite thick, not abbreviated very much. It's the thing the repair manual assumes you've already read, so you know what the different pieces are there for and how they do it.

People just don't as often make big PDFs of that to share around.

Beyond that, there's a whole humongous library of technician training course materials on TIS, for questions you might still have even after reading New Car Features.

 

So, when you put it in neutral, what RPMs do the MGs show?

 

When mine showed state of charge on the hybrid battery (in my Gen 5), I was surprised to learn that the charging rate in the CHG mode was only about 15 amps, (probably to preserve fuel economy). Hard braking delivered nearly 200 amps regen power.

Unfortunately, that feature seems to have been removed from Car Scanner.

 

MG2 shows the RPM directly related to the car's road speed, according to the final drive ratio and the MG2 reduction ratio.

MG1 shows the RPM you can find on the nomograph by plotting a line between the engine RPM and the ring gear RPM (for which you can use the MG2 RPM reduced by the MG2 reduction ratio, or the wheel RPM increased by the final drive ratio).

There is no change in those RPMs from the instant before you put it in neutral. (After that instant, of course, they will continue to vary according to the car speed and engine RPM, always according to the math above.)

Whatever those RPMs are whenever you decide to shift again from neutral to another selection, there is no RPM change at that instant either.

 

Fact or wishful thinking?

 

Well, I don't know what Car Scanner Pro would show, not having used it, but are you thinking maybe it would show different RPMs than Techstream, and Scan Gauge II, and Autel AP200, which I have used, all unanimously show?

And if you could find an app, whether Car Scanner Pro or anything else, that did show you different numbers than the math with the transmission's gear tooth counts will tell you, how would you explain the numbers shown by such a hypothetical app?

 

I know this has you triggered, but I don't believe a Prius can coast in neutral without computer/electric assist. OK?

 

Whatever you want to believe is OK for you.

Anyone who has spent a moment coasting a Prius in neutral with the power for any "computer/electic assist" turned off has likely reached a different conclusion. I certainly did.

 

What convinced me was while I was in a car wash, it asked me to put the car in neutral. As the engine came on and off, the drag on the drive train remained the same. This would be impossible without computer assistance.

 

You've owned a couple generations of Prius—which one was this where you're saying the engine came on and off while the car was in neutral?

What you think the car wash experience tells you about how neutral works seems to depend on your armchair reasoning about what is or isn't "impossible without computer assistance".

You'd get a great reality check on that by just getting out of the armchair and taking the simple step of rolling a Prius in neutral, with no power for any "computer assistance", and learning what anyone else learns who does that. It seems you still, while hijacking yet another thread to rehash the same topic, have yet to do that.

This is the same pattern as in the thread where you thought the 12-volt battery in your car had to be AGM, and from post #66 on page 4 of that thread clear through post #150 on page 8, you refused everyone's suggestion to just go in your car and look, while dismissing what people who had looked were telling you ... and then you finally went and did look, in post #153, and that's when you learned the same thing they'd been telling you for 87 posts.

At this point, so that this thread about the Car Scanner Pro app doesn't end up completely hijacked into another thread about how Paul thinks neutral works, I'd suggest these ideas for traffic flow:

Post here if it's about the Car Scanner Pro app, and its features and limitations.

If anyone reading this thread is curious for more about how neutral does or doesn't work, and how Paul's ideas on that contrast with the 'consensus', there are existing threads for discussion of that; here's one of those.

 

I'm easily convinced with the right evidence. So far I haven't seen it.

 

You're rolling through a carwash in neutral. Suddenly the engine comes on, and there is no detectible lurch in the drive train. If it were a simple matter of the transmission freewheeling, there would be some backlash as the engine engages. There should also be some drag due to the rare earth magnets in the motors. This does not happen; it's undetectable to me at least. This is why the Car Scanner would be relevant to this question; it would show what is actually happening when you shift into neutral. The only way that this could be accomplished is for the computer to eliminate the torque in real time, proactively with the electric motors.

 

In the moments when the car is cranking the engine to start it, or bringing it to a stop, the car always does use coordinated torque at both MGs to minimize the lurching of the car.

Outside of moments when the car is cranking the engine or bringing it to a stop, there's no need for such shenanigans.

The most interesting part of your post is where you say "Suddenly the engine comes on" while your car is in neutral. You haven't yet said what generation that was. You've had both a gen 3 and gen 5, right? Which one starts or stops the engine while in neutral?

Car Scanner is only one of many scan tools that can retrieve and display values from the car's ECUs. If you're interested in "what is actually happening when you shift into neutral", the PIDs that are available for you to peruse include MG1 and MG2 and engine RPM, and MG1 and MG2 torque.

If you do peruse them, whether with Car Scanner or any other suitable tool, you'll see that "what actually happens" at that moment isn't very much. Things were spinning at certain RPMs the instant before, and they're spinning the same RPMs the instant after. The torques go to zero, as the word 'neutral' conveys. Following that moment, the RPMs will either gradually pick up (if you are rolling downhill) or drop off (uphill or flat).

The gear ratios that always connect those RPM readings with the engine RPM and axle RPM are things you can look up. They're fixed values for any given Prius model and trim. You won't see the RPMs depart from those relationships.