Hello everyone I need some help. Ive read numerous posts about the ABS/Brake light staying on and it all seems to relate to the speed sensor however most of the posts people mention their speedo doesnt work. My vehicle the speedo does work but ive notice that it seems to be in the area of 5-10mph off not sure if its because of the tires or related to the speed sensor. My question is could my problem still be the speed sensor even though the speedo does work but is off a few MPH??????

 

Did you go up a size from the fac tire size? My speedo is of by aprox 2 miles with the 20's and the 30x9.5's

 

when is the last time you had your brakes serviced and do you know if the techs did the service do you know if they bleed your brakes

 

I don't get why the braking system on the rear wheels would interfer with speedo?????

Look under the truck at the spare tire and read the tire. A lot of the time when someone changes out the tire to a different size (it might have been you) they forget about the spare.

The D came with LT235 75 R15 or an upgraded wheel of 31X10.5X15 LT. If you had one size and then went to the other this would through it off like DR0318 is suggesting.

 

Here is a link that anybody can use to calculate the diff in speed between two tires.
http://www.discounttire.com/dtcs/infoTireMath.dos