Remember calculating which speedo drive gear would make your speedometer and odometer read accurately after a gear and tire size change? if you own a new JK wrangler, those days are gone. Now the speedometer (and, of course, odometer) are recalibrated via the vehicle's computer. your dealer can do this, although most look at you like they're deer caught in your headlights when asked, or they say they can't recalibrate beyond stock parameters. who cares? Pro Comp has a nifty new product called the Accu Pro Speedometer & Odometer Calibrator that will calibrate your speedo and odometer to read accurately.
The Accu Pro comes with CD-ROM software, USB cable, and a diagnostic port cable.
David at Northridge 4x4 in Bremerton, Washington, sent us an Accu Pro, so we could quickly get our JK done and will be able to recalibrate when we change tires and gears again (and again, and again). David will be happy to help anyone purchasing the Accu Pro from Northridge 4x4 with any questions they may have. we can't see too many questions arising as it's simple and easy to use. we're happy that something actually got easier to do. Goodbye plastic gears.
Follow along, and we'll show you how easy the Accu Pro is to use...
A screen pops up with an overview and instructions. | 
Attach the Accu Pro to your computer using the supplied USB cable. the Accu Pro will check for any software updates and will tell you when it's finished. Unplug the unit and take it out to the Jeep along with the diagnostic port cable and your ignition key. | 
Put the CD-ROM into your computer and install the tuner software. |
Using a carpenter's level, measure the exact height of your tire. Don't go by 35 inches, 37 inches, etc. as they're never really the exact diameter molded into the sidewall. Plus you have static-loaded radius to take into consideration. the Accu Pro will let you input the exact size of your tire in 1/4-inch increments. | 
Turn your key in the ignition all the way to "Run" but don't start the JK. | 
While this photo is taken from the outside looking in, you need to be sitting in the Jeep with the doors closed. Plug the supplied cable into the Accu Pro and the JK diagnostic port. then, using the up and down arrows and y and N keys, follow the simple directions displayed on the Accu Pro's screen. Do not unplug the unit or turn off the key during this programming sequence until prompted to do so at the end. you'll be asked to input tire size to the nearest 1/4 inch and gear ratio (if you changed ratios, that is). the Accu Pro will program gear changes to 5.13:1. while the JK uses tire diameter only for the speedometer and odometer, programming in your new gear ratio will correct transmission shift points. Once programming is completed, the Accu Pro will tell you programming was a success. that's all there is to it! |