but couldnt find anything that fit what i was wanting to know, so new topic time!

is there any way to 'fix' the speedo/odo to tell the accurate mph/miles when you put bigger rims on the box?

thankies :D

 

bumptacular

 

nope...even if you did your milage will still be off and out of your favor too...sorry its sucks but what can ya doo...

 

damn, that really sucks. i was hoping for some way to tinker with the ECU or something to correct it.

blah

 

I thought you could have the speedo adjusted... Correct me if I am wrong somebody but I am pretty sure it can be done for a pretty penny

 

personally i would rather have the odo properly set so i dont max out mileage when it really isnt.

but avoiding tickets would be nice to. i fugre there has to be a way to mess with the ECU or something..

 

If you match the new tire overall height to the stockers your speedo should read the exact same regardless of the size of the rims.

 

The speedo is about 3% optimistic and the odo is about 3% short of actual, and they are both sourced from the same signal.

Easiest way to correct the speedo would be to move the markings... or go to a tire about 0.4 inch larger like I did (of course my odo is now 6.1% short).

 

There are adapters that will change the signal by a % that you choose (+ or -). I don't have the links with me but search under "dakota digital" and "yellowbox". While I don't know of anyone using them on Scions, they are both widely used on a variety of cars, trucks, and MCs.

 

Here you go...

http://www.dakotadigital.com/index.c...rod/prd126.htm

If it works on the Scion, it is probably a pretty good investment at only $80.

 

The problem with any of the adapters is that the single "SPD" lead between the ECU and the "combination meter" feeds not only the speedometer and odometers, but the skid controler and actuators (through the comb. meter).

If one places an adapter in that lead, and adjusts it to correct the odometer, for example, the speedometer will be made to be even further off, and vice-versa.

Also, of course, adjusting the signal on that lead will have unknown effects on the VSC system and any other systems fed a signal from the combination meter that was derived from that single lead.

Personally I'd rather have the speedo reasonably accurate and I can make mental corrections to my odometer if necessary (I multiply whatever it currently tells me by 1.06 - that's 6 miles every hundred).

I'll just stick to tires with outside diameters within a few percent of OEM spec. My current tires are 3.1% larger than stock and I'm happy with the speedo and odo results.

Tomas

Reference: CombMeter.pdf