Speedometer correction?

[NJshadow93]

Thanks for looking!

Does anyone know if the speedohealer adjusts the speedometer and the odometer?

Pretty sure it just calibrates the speedometer, which, in turn, calibrates the odometer. The only reason for the odometer being inaccurate is if the speedometer reads too fast or too slow, which the Speedohealer corrects.

 

[CXS]

Just an update, I still haven't found any mention of this calibration you were talking about?

Toyota 4Runner 2005 Navigation System Owner's Manual

Page 78

"The tire change calibration function will be used when replacing the tires. this function will adjust the mis-calculation caused by the circumference difference between the old tires and the new ones. If this procedure is not performed when the tires are replaced, the current position mark may be incorrectly displayed."

 

[NJshadow93]

So it sounds like it only really affects your position on the map rather than your speedometer?

 

[BlackWorksInc]

Pretty sure it just calibrates the speedometer, which, in turn, calibrates the odometer. The only reason for the odometer being inaccurate is if the speedometer reads too fast or too slow, which the Speedohealer corrects.

Yes, the Speedo-healer will correct the issue, I am going to get one eventually to satisfy my CDO. :der:

Toyota 4Runner 2005 Navigation System Owner's Manual

Page 78

"The tire change calibration function will be used when replacing the tires. this function will adjust the mis-calculation caused by the circumference difference between the old tires and the new ones. If this procedure is not performed when the tires are replaced, the current position mark may be incorrectly displayed."

Ah okay, found it... the correction of the speedo (if it does correct it, manual and TIS doesn't really verify one way or the other) is a by-product of the Navigation unit. The calibration is to allow the Nav unit to measure where it is and has gone without relying heavily on the GPS and uses the GPS to correct its internal map. There is no way to calibrate the Speedo via the TIS Techstream or any other method, unless you have a factory navigation unit (again, TIS does not verify either way, and without a Nav equipped truck I can't say for 100%, but I'll trust you on it. )

 

[TRDCal]

The only reason for the odometer being inaccurate is if the speedometer reads too fast or too slow, which the Speedohealer corrects.

Ok yah makes sense. I just wasn't sure if both meters were fed by the same wire or if you tapped into the speedo wire after the odometer, if that's even possible.

"The tire change calibration function will be used when replacing the tires. this function will adjust the mis-calculation caused by the circumference difference between the old tires and the new ones. If this procedure is not performed when the tires are replaced, the current position mark may be incorrectly displayed."

The way that's worded, its like they only intended it to calculate the difference between new and worn-out tires. Not for people to put bigger sized tires on. When you go to calibrate, do you have to drive a few miles before it makes the change? I wonder if it needs the gps signal to recalculate the size which would explain why its not an option in techstream

EDIT: Got distracted while typing my posts...looks like BlackWorks had the same epiphany but sooner

 

[CXS]

The way that's worded, its like they only intended it to calculate the difference between new and worn-out tires. Not for people to put bigger sized tires on.

Really? It states "circumference" and that's what changes with any/all tires changes in my experience. As I stated initially, my speedo is accurate with larger tires. Was that the intent of Toyota? I don't know nor do I care, I simply was stating my speedo is accurate.

When you go to calibrate, do you have to drive a few miles before it makes the change? I wonder if it needs the gps signal to recalculate the size which would explain why its not an option in techstream

I have no idea, I found the recalibrate setting long ago and use it with tire changes. it's not something I've analyzed.

 

[ARK_SWAMP_RIDER]

I tried this calibration on mine when switching to 285's, couldn't really tell a difference. It was still off. My understanding was that it only affected your position on the map. I installed a speedohealer and yes, it does affect the speedometer and odometer. My issue was/is that the speedometer and odometer are off by different amounts. I chose to calibrate my odometer so it's accurate, and while my speedometer is close, it's still off by 2-3 mph at 70.