Anybody know how to reprogram wheel speed/ speedometer

It has been discussed before and I don't believe it is possible without specialized programming tools......and inside knowledge of the code involved.

 

Some people here have corrected their tire size to correct speedometer deviation

I have not heard of anybody correcting the speedometer. I doubt the dealer would be able to either. Their main software interface is TechStream which has been used my many people here.
If is is possible, @Elektroingenieur may be able to find if it is in the techinfo documentation. Otherwise, likely Toyota Design Engineering would be the only ones capable of doing this.

 

I found this but have never tried it, good luck if you use this.

Official home page of the Yellow Box Speedo Recalibrator

 

Yep. Your right - it is very advanced car.

 

The Prius is a car designed primarily to be low polluting and secondarily to be fuel efficient. Why would Toyota want to spend engineering resources to permit modifications beyond those goals?

Where is the financial payback if they chose to develop those features? If you could present a case for increased ROI, I expect Toyota would be all ears.

 

I think it's rude to tell someone when you're gonna hit the ignore button, but I might make an exception, lol.

 

What I find interesting is that Toyota lies about the speed on the display apparently deliberately. If you use a scanguage or other OBDII device, it will show the speed accurately, or very close to it. The car knows its speed but it want's us to think it's going faster than it is. And apparently, most other cars are doing the opposite so drivers think they're going 45 when they're actually going 65.

 

No, no, no: speedometers are never supposed to indicate you're going slower than actual. And since deadly accuracy is unachievable, they err on the side of caution, intentionally: indicate you're going a little faster than you are.

 

YOU are making the mods.
YOU are responsible for whatever that causes.

Toyota is not responsible to take into consideration any and all mods that owners might make.
Get over it.

You can "recalibrate" your speedo with some little pieces of masking tape.

 

As @Sam Spade observes, this topic has been discussed many times before; as far as I know, you can’t.

The Repair Manual (available by subscription to techinfo.toyota.com) has a list of the “Customize Parameters” that can be changed using a Toyota Techstream diagnostic system, and there isn’t one for tire size, outer diameter, revolutions per mile, or any similar parameter. I checked several other Toyota models, including some more often seen with non-standard tires and wheels, and none has such an option.

It’s conceivable that some third party might have developed a way to reprogram the skid control ECU or combination meter, but I’m not aware of one, and would advise against it, in any case.

Not necessarily. For the 2010 Prius in the U.S., the two sizes of factory-installed tires were P195/65R15 and P215/45R17, for which the difference in diameter makes only a small contribution to speedometer error.

 

I'm sure that the discrepancy is part of their cya program. It's just sad that it's necessary. As to my 45-65 comment in post #11, I hope you know that was sarcasm generated by people in Chevy Suburbans passing me on the shoulder at over 100 mph.

 

Might be your only option.
Another case of "Don't confuse me with facts, my mind is made up."
Good luck.

 

Car so advanced, trunk won't even open with key (sks) next to trunk with engine on.