This is my first post, so I hope that I am doing this right. I recently bought my truck (1998 xlt 3.0L 4wd) from a family member. The truck has been sitting since 2014ish, and has the ABS light on; I have no idea if that is related to my problem. When I got it, I noticed the truck seemed to drive really slow. It turns out that the odometer is 10 mph too fast. Ex. I'll be driving 40 mph but the odometer reads 50 mph. I have no idea what it could be, and when I took it to my local Ford dealership for a full checkup, they didn't point out that any electrical related to the odometer was faulty. I've spent so much time looking for someone with a similar problem, but I personally can't find anything.

 

How have you verified that it is reading high ?

 

Welcome to the forum

Ford didn't fix or find the ABS light issue????
That would be very bad on their part

On 1998 to 2000 Rangers the Speedometer and ABS share the same speed sensor on the rear axle, but a problem with this sensor would be no Speed on speedometer and ABS light on
So its odd

You can put in a new sensor, just 1 bolt to take off to change it, on speculation, as said it would be an odd failure mode, it's on top of the differential, not hard to get at
Called the rear axle ABS sensor, or mistakenly a VSS, lol
Also give the 2 wires and connector a good like for corrosion

Do the tires look small for the vehicle?
Smaller diameter tires cause speedometer to read higher MPH than the stock size that came with the truck

If you look at the back side of drivers door you will see the Build label, it will have the stock tire size the vehicle came with

 

I originally realized after passing one of those construction signs, "your speed is __." Once I saw the sign was reading lower than the odometer, I used a GPS speed app and went down the freeway to confirm.

 

So Ford did say they'd fix the ABS sensor problem, but I don't know if they weren't sure if they knew exactly what they were doing, or just trying to price gouge me, but it would supposedly cost $600+ to fix the issue and as they said: "it wasn't pressing, and was most likely caused by faulty wiring." I didn't feel it was necessary at the time, especially paying $700 for the inspection.

As for the tires, I checked, and they are the same size as on the sticker.

 

Then I would just replace the rear axle speed sensor

Google: 1998 ford ranger rear axle abs sensor replace

The is a 3min video on how to do that

A Ford brand sensor is $40, but Dorman makes same sensor and its $15, most local auto parts places should have Dorman
And because its so easy to change I would get the less expensive brand

The next step will be much more complicated in diagnosing the ABS and speedometer issue, the axle sensor is the only "common" connection between those two things