I knew that my speedo was going to be off after re-gearing and changing the tire size on my Toyota FJ Cruiser. During a trip this last weekend I figured the error to be about 10%. Prior to the re-gear modification I had done some research on devices used to correct the speed and found one from Hypertech. (Part # 730108)

On Monday I ordered one through Predator 4×4 here in Colorado Springs. They had the device for me the next day.

The Speedometer Calibrator Module is a small black box with a USB interface for programming and a socket to plug it into the wiring harness in the FJ.

Programming the device involved plugging it into my computer and loading the device drivers, Windows 7 was able to download the drivers off the Internet. Once the drivers were installed I started the configuration software. The software allows the original gearing and tire size to be entered along with the new tire size and gearing.

Once the data is entered, the program unit button is clicked and the the system is ready. The programming can be checked by clicking the “Read Device” button.

To complete the process the device needs to be installed in the FJ. If you follow the Hypertech instruction the installation will take some time with the dash fully torn down. I my case I removed the 2 screws that hold the drivers side glove box and the top of the Speedo cluster was revealed.

With the harness exposed I unplugged the connector from the left side of the speedo and inserted the Hypertech harness extension. I plugged the  Calibrator Module into the harness and used double sided sticky tape to stick the module to the heater duct. Using a few tie-wraps I secured the harness, replaced the glove box and I was down. The total time spend was about 20 minutes.

A test drive showed the speedo to now match the speed on my GPS. This is an easy modification and should be completed for any tire or re-gearing changes.