AEV's ProCal Module is a hand-held powerhouse! This essential tool provides JK owners an easy, low-cost way to make a variety of useful changes not offered by the dealer or any other re-programmer. Topping the list is the ability to correct the speedometer and gear ratio when larger tires are installed. With the speedometer left uncorrected, there is a major degradation in the performance of the stability control (ESP), transmission shifting, and engine performance. The best part of the ProCal is that it isn?t just for correcting the speedometer. The Tire Pressure Monitoring System can now be recalibrated to better suit aftermarket tires without triggering the dash light. Further, the ProCal Module makes it possible to activate daytime running lamps, "one-touch" turn signals, enable a temporarily increased engine idle speed for winching, clear engine codes, and even has a feature to help align the vehicle perfectly for optimal ESP performance.Users will also love the ProCal Module for the other options it provides. Their vehicle's factory Tire Pressure Monitoring System can now be recalibrated to allow for lower street pressures without triggering the annoying dash light. Further, the ProCal Module makes it possible to activate daytime running lamps, one-touch turn signal options and temporarily increase engine idle speed for winching.The ProCal Module is equipped with a series of easy-to-use dip switches. By reading the simple code card included with the Module, any user can quickly dial in a code for the desired recalibration. From there they simply plug the Module into their vehicle's OBD port and wait for the horn to honk. The whole process can be completed in mere minutes and it's just as easy to reverse.