I thought I'd share my experience with you all, maybe it could help someone.
When I bought my 99 2wd ranger the first thing I nioticed was the speedometer acting very strange. Seemed to work ok to abot 30mph then it would go to 0 and jump back up. after driving it some I realized when you gave it gas it would stop working then when you let up it would jump back up. I stopped at the parts store and picked up a speed sensor and when I crawled under to change it I was suprized to find out that the trans wasn't even drilled for a speedo gear, just a casting boss that hadn't ever been opened up from the factory. Of course I figured maybe the speedo was bad so I change the cluster from my parts truck....same thing. Of course me always doing stuff the hard way I finally pulled out the repair manual and read it. It seems that the speed sesor on my truck is combined with the abs sensor in the rear axle. So this evening I pulled out the abs sensor and cleaned it with carb cleaner and reinstalled it. The speedo works normal now.
John

 

Good fix.

Ford had the rear axle ABS sensor doing double duty as the speed sensor from 98~2000. Speedometer problems and erratic shifting (automatics) are common problems on these years when the ABS sensor starts to get flaky. Sometimes it will also display a CEL for code P0500 but not always.

 

Good info thanks, Mine didn't produce a code.
John

 

jokes on them...my truck doesn't even have ABS!!! haha. thank god...abs scares the hell out of me...i'll keep this fix in mind for the future...

 

Your 94 has a cable driven speedo.

 

I have ran into the same problem this week. Tried the gauge first and no help. Bought a speed sensor and cant find it on tranny. Bought the book and learned about the double duty sensor on the rear axle. Found a sensor that looked something like the one I had purchased, but when I took it out it looks completly different. It looks like a simple short probe. Is this the correct sensor or am I completly missing it? Thanks for any advice...

 

First of all what year. What sensor did you buy?

 

The sensor is located on the top of the differential. I took mine out and cleaned with carb cleaner and the problem went away. Took the one I bought back and cashed it in for the 20 bucks I paid...lol
John

 

Yea, the abs sensor on top of the differential... It didnt fix my problem tho... Im guessing my problem is deeper? Like maybe inside the differential? I might have lost the part on ring gear that flags the sensor?
Signed,
Out of luck

 

Make sure the needle doesn't bind.

You also my have loose connection.

Possibly a loose tone ring in the rear end, but i doubt it.

 

No loose connections that I can see... I think I will try pulling the sensor again and maybe have someone sit in the truck with ignition on and watch the speedo as I flag the sensor to and fro... Im guessing I could isolate the problem to either wiring to the front or in the differential, depending on if we have any speedo movement or not...

 

Keep in mind the 99 has an electronic speedo. So there maybe a mechanical portion of the cluster which is bad.


I have personally had problems with the wiring harness for the back half of the truck(mine was fuel related but the run together). In my case the cab seemed to settle on the the harness rubbing it till shorted out under the truck.

To check for this will need to get under the truck right under the drivers seat. Look for any rubbing of harnesses that come threw the body. Especially where the connectors are on the black plastic shelf. This may not be your problem buts it free to look at.

 

Alright, I like that free part... I will do some checking, as soon as I get a night off.
I will get back with ya'