Speedometer Calibration

Sonny Bibb

Member
Sep 11, 2026
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Wondering if anyone on here can help me out I have a 2000 Mustang GT with a 2004 4R70W transmission apparently in 2004 Ford decided to change the output on the speedometer sensor PPM from 6 to 24. I have used my SCT Livewire TS+ and using the maximum rear end gear ratio option of 5:13 and maximum tire revolutions per mile of 900 revolutions per mile. The best I can get is at a GPS speed of 60 my speedometer reads 110. I have the SCT Advantage III software ( got it 3 days ago ) but nothing that I have tried so far with it seems to make any difference to the speedometer reading. I am in touch with SCT support but well you know. I am trying to make changes however Advantage III won't let me change scalar values even though the value is within the minimum - maximum values this is occurring in transmission gear ratios and axle ratio scalars and pretty much any value I try to change. The changes that I do mange to get through do not seem to have any impact what so ever on the car. Any suggestions, advice or input would be greatly appreciated.
 
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