Hypertech 732500 Speedometer Calibrator

Running LT315/75R15 on my 2001 Durmax the speedometer was always about 7mph too low at 65mph although my Edge tunner would show the correct speed the speedometer was incorect. I was finally able to correct this with the hypertech.. it took some trial and error playing with the tire size input to get it to match with my GPS. I did have problems updating the unit with the correct firmware. when I called Hypertech tech support they recomended trying a different usb cable because he said the ones that come with the unit are really cheep.. so i found a old USB microB cable and it worked the first try.. other than that no problems .

Recieved at 4:00 pm on Friday afternoon. Updated through the Hypertec website. Installed it on my 97 Chevy at 5:00 pm. Took 4 tries to get my speedo to match the cell GPS. The tires are 29.5" but i had to keep making the tire diameter smaller than that to adjust the speedo readout. I finally settled on 28.0" in the settings, and the speed now matches GPS. Long test drive and the truck runs and shifts much nicer. Gears shift when they should. Did some calculations and found that my rear ratio 'may be' not stock at 3.73, but might be 3.90 gears. Or the internal programming may see the numbers input differently than measured. At any rate, the Hypertec unit worked exactly as required. Recommend.

Be careful when you buy refurbished/used products like this. I missed being able to return it by 2 days. My problem is that it was used before I received it. This product only works with one vehicle at a time. I got the code 91. It says that I need to return the vehicle back to stock before I can program my truck.

All you have to do is follow the prompts. I did have to update it for my truck and did exactly what the instruction said. ( need a non-apple operating system) I did have to do it twice to adjust the speedometer to the GPS speed but in the end, my spam appears to be right on target. Would buy again.

Downloaded the appropriate software for the vehicle. In the vehicle the progarmmer went through all the steps and completed the update, but it didn't change the speedometer reading. I road tested it after each programming attempt and still no change comparing the speed to a known accurate GPS speedometer. Four times and still nothing. I tried different diameters just to see if it would work but still it said it programmed the ECU 100% but still no change. Returned. Going with HPtuners and buy credits just to change the speedometer as the truck runs real good on regular gas no tune needed. It's faster than my Tahoe that has a premium fuel tune. I'm not new to performance tuning and I'm not going to waste time trying to get some poorly made tool to function.