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Jim
Jim, Auto Service Technician
Category: Ford
Satisfied Customers: 263
Experience:  Ford Senior Master Technician with 30 years in the Automotive Field.
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How do you recalibrate the speedometer for larger tire size ...

Customer Question

How do you recalibrate the speedometer for larger tire size on 99 Ford F150 lariat 4x4 currently running 35's and I know the spped is off and the shift points
Submitted: 9 years ago.
Category: Ford
Expert:  autodoc_2000 replied 9 years ago.
You need the Ford scan tool. Call around to shops and ask them if they have a NGS scan tool or you will need to go to your local Ford dealer. You need to input the tire size into the scan tool in order to calibrate it. It is not hard to do.
Customer: replied 9 years ago.
Reply to autodoc_2000's Post: been to all 5 local dealers here, they say they cant recal the sppedometer, i would need to buy the $400 super chip from a performance shop, I know there has to be a simple way to do this without spending that amount of money. I have checked several shops in the area as well without any results
Expert:  autodoc_2000 replied 9 years ago.
If you use the NGS with the green service card you can configure the module for this. I have done this.
Customer: replied 9 years ago.
ok where do I find this NGS with green service card, nobody around seems to know anything about it, not for the 1999 F150
Expert:  autodoc_2000 replied 9 years ago.
I just tried it on a 1999 f150 in our lot. Any Ford dealer will have a NGS. With the green card installed go to GEM and customer preference. From there you can go through and change the tire size or revolutions per minute, gear ratio if you wanted to and other items.
Customer: replied 9 years ago.
ok I have called every dealer within 50 miles of here, nobody has this ngs, or willing to say they have it to calibrate the speedometer, any other suggestions
Expert:  autodoc_2000 replied 9 years ago.
I do not know what else to say. The NGS was sent out to all Ford dealers in the mid 90's. I currently am employed in an independent repair facility and we purchased one shortly after I started working here. I know that Ford has come out with other scan tools, but the dealers around here still have and use their NGS.
Customer: replied 9 years ago.
ok the NGS must be something used where you are at, the dealers here said they have never heard of such a thing and dont have one, i spent hours on the phone and driving to local repair shops without finding a single one, any other suggestions
Expert:  autodoc_2000 replied 9 years ago.
Customer: replied 9 years ago.
ok I believe what you say that there is such a creature, but it still stands that none of the dealers around here are willing to use it for speedometer calibration, dont know if they are unaware that it can or just dont want to do it, but I cant get one to calibrate my truck, are there any other ways to do it?
Expert:  autodoc_2000 replied 9 years ago.

This is the only way I know of to program the bigger tires into the computer.

Customer: replied 9 years ago.
ok can we open this back up to other mechanics to see if they have any other ideas
Expert:  Jim replied 9 years ago.
FORDs module will not go that large of tire size... The only way to recalibrate the speed sensor is thru FORD racing. You can buy a little speed sensor converter from them. It comes with instructions on which switches need to be in which position for the tire size and gear ratio... I have installed several of these on vehicle that have been regeared for stret and strip racing.. Basically you are tricking the computer by changing the signal pulse... or ac voltage... Without this device your speedometer will not read correctly... And per FORD there is no other way.... Contact ford racing online they can helpyou get the speedometer converter
Jim, Auto Service Technician
Category: Ford
Satisfied Customers: 263
Experience: Ford Senior Master Technician with 30 years in the Automotive Field.
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