Odometer/Digital Speedometer/Analog Speedometer factory tolerance? How are the two related?

Does anybody have the:

Digital Speedometer tolerance?
Analogue Speedometer tolerance?
Odometer tolerance (if there is one)?

How are the above related? Is the odometer dependent on the digital speedometer , analogue speedometer, or does it have it's own way to measure distance?

When driving I have tested with a few different GPS apps and seen the same results...
GPS app reads equal mph or greater by 1 mph than the digital speedometer.
GPS app reads greater by 1-2 mph than the analogue speedometer.
Both of these are an issue...

Additionally, if either of these are tied to the odometer, that would mean the odometer is not correct unless there is a factory tolerance of +/- x.

Can anybody help me out with the above?

Thanks,
Dan

 

Why is this an issue?

What if the factory tolerance is +/-5%.

Why not take it to a dyno operator and see what those results are and compare it to your GPS?

I did....

https://www.tacomaworld.com/threads/speedometer-off.435381/#post-12591638

 

@jsinnard not an issue at all! . Actually, I'm stoked about your post....was hoping somebody could provide the no kidding Toyota spec. If it is actually +/- 5 % that is awesome! I'm looking to upgrade my boots to 265/75/16's soon...but I'm OCD about my odometer being off. I could give 2 about my speedo...I care about actual mileage on the odometer.

This leads to my other question...anybody know how/what the odometer tracks off of?

My analogue speedo is reading ~ 2 mph faster than actual speed, so if I upgrade to the 265/75's I should be closer to the reading on the speedo....just wondering about mileage.

 

Wheel speed sensors feed the skid control ecu; then sends it via CAN to the instrument cluster.

Here are the two reference charts in the service manual.
The first is based of a dyno comparison.
The second is based off a Techstream comparison.
Looks like you're within 'spec', considering you're comparing it to gps.

 

Once you find out how much your speedo is off, translate the same percentage to the odometer.

 

So my analogue speedo might be right on the money if I get the bigger tires...according to tirecalc:
https://www.tacomaworld.com/tirecalc?tires=245-75r16-265-75r16
I should be right on if my actual speed right now is slower than what my analogue speedo reads.

 

It's possible.

 

@splitbolt looks like R31 may be my speedo then? Still don't understand why analogue and digital are off and which one correlates to the odometer.

I understand wheel speed sensors send the data to the ecu, but do you know how the odometer uses this data? Does the odometer track off this digital data because odometer is digital as well?....that would make sense...

So I guess the analogue speedo's are just "off" due to the digital-analogue conversion....why even have an analogue reading if it is sooo inaccurate?

My digital speedo is actually pretty accurate being that it's only about 1mph off...but if that's a factory acceptable tolerance than technically I can upgrade my wheels and my odometer will still be "within" specs....

 

T!ts

 

Just trying to justify to myself I can upgrade to the 265/75/16's and still be legally/technically within Toyota specs for speed and distance....AND if this is correct I don't have to worry about recalibrating anything??!

 

Do you have the multi-information display in the center of the instrument cluster?

 

Yea...I have a 17 SR5.

 

Keep in mind that tires listed as 265/75/16 sizes will vary in real world measurements.

 

Gotcha, thanks but the tires are only one size bigger than factory, so I'm pretty sure they will still be within tolerance, but I understand they may not due to not exact sizing...

 

Plus, tires wear. Plus, outside turn wheels go further than inside turn wheels. Plus, a 265 65 16 for example might be a different circumference than another brand 265 65 16.

How close do you want?

 

What I am understanding from the block chart above is digital speed and odometer in fact both come from ecu which makes sense as they are both digital. Soooo I guess my digital speedo and odometer are pretty accurate, but over the lifetime of my truck, they may actually be wayyy off after 400,000 miles.

Additionally and technically the service manual demonstrated earlier it's acceptable to be 2 mph off....so you could in theory go up a little in tire size and not be out of tolerance.

Side note-Any idea how analogue speedo works?

 

As long as I'm in tolerance by Toyota (looks like that is a couple mph) I'm not worried about putting a size bigger and what my odometer says now will be ok by the book....

If I went to 33's or bigger I may feel the need to actually have stuff recalibratd....I know my head hurts...it's hard to be perfect

 

I should have put this one in post #6.