OK, so I've read the posts about having the ABS light on / the speedometer not working. I've come to the conclusion that it is usually a)the rear ABS sensor located on top of the pinion on the rear end or b) the programmable doohickey instrument cluster. Of course, it can be corroded connectors and wiring and such, but these seem to be most common. I just bought a '93 F250 XL with the 351/5 spd. ABS light is on, and speedo is intermittent (usually not working at all, but occasionally starts to dance, somtimes going full sweep, and sometimes trying to read correctly). I don't have the dying engine problem due to fuel shutoff when it hits the speed limiter. I did remove the sensor in the rear, and cleaned it off. It had practically NO shavings on it. It was easy to get to, since the truck used to have a gooseneck hitch in the bed which is now gone, and there's a one-foot-square hole in the bed directly over the sensor. I'm going to replace the sensor, since it's practically free when you have a friend behind the Ford parts counter.

SO, how many of you would bet on the sensor, and who's betting on the cluster, and why? I'm sure hoping for the sensor!!!

 

It could also be the teeth on the tone ring behind the ring gear in the axle. It's the ring the sensor reads off. Sounds like you have a bad wire somewhere.

 

Yeah, that's totally possible, too. What are the chances that it's one of those, as opposed to the sensor or the cluster? I can check the teeth on the ring by moving the truck with the sensor removed, right? Remember, I have an "inspection port" in the bed where I can see it.

 

It was, in fact, the RABS sensor. That was one of the easiest fixes ever!

 

To check that, you'd have to drain the gear lube and remove the rear diff cover.

 

Huh?

 

Thats what I was replying to.

 

How's about if I jacked up the rear of the truck, removed the RABS sensor, and had someone turn the rear wheels by hand, while I stand in the bed of the truck and look at the teeth on the tone ring? I can see the teeth plain as day, and it would be a lot easier than removing the rear cover and draining the fluid. I didn't need to do it this time, but I could if necessary.

 

Yeah I guess you could do that, but it's not hard and it's a good idea to change the fluid. All you do is remove the bolts on the cover except just loosen the top one. With a drain pan under it, pry off the cover and once most of the fluid is out, remove the top bolt and take the cover off. Use some more gasket maker and put the cover back on, bolt it up, and put some fresh fluid in the diff.

 

Yeah, I've done my share of those. But I sure thought it was cool to be able to just look in there and see the teeth and fluid level without such a mess!