Speedometer output

[BHaden]

I recently put 34 inch Pirelli Scorpions on my 2003 6 speed. Love the tires so far but the speedometer is off by right at 10%. Would like to correct the issue but can't determine how the speedo gets its signal. I found one sensor on the rear diff that turned out to be a sensor paired with a tone ring as well as 3 different connectors on the transfer case. I disconnected them one at a time and drove to the end of the street and back only to find the speedo still worked. Did I miss something? Is the ABS throwing me a curve? Am I going to get an electronic programmer of some kind that will allow me to reprogram for tire size? Help would be appreceated.
Thanks,
Bruce

 

[Darkbloodmon]

You're going to have to get the it programmed, for the mean time use a tire calculator and drive according to the difference.

 

[BHaden]

10% is not hard to figure while driving, it's just annoying

 

[Darkbloodmon]

Unless you're running tunes where you can adjust that parameter in the ECU its not really worth it given the small difference.

If you're running 37s and re-gearing its a different priority.

 

[Ozymandias]

It takes the signal from the ABS, so it must be corrected in the ABS unit.
Means, DRBIII, AutoEnginuity or several Tuners can do, there are even gadgets out there just for speedo correction but they are to expensive from my point of view.

 

[Motorhead]

Smarty jr will do tire diameter corrections for the speedometer.