2004 Ford Ranger 4x4 XLT - speedometer problems (that are more than just it bouncing)

[mhuitt]

Question: I've replaced the wheel sensors, the hubs, the ABS wires, and everything I can think of (that I can do) to fix this. Still a problem. The speedometer is fine for about twenty minutes, then it'll start jumping all over and feels like the truck is losing speed when it does that.

What could it be?

 

[sgtsandman]

Just to be sure, you checked the ABS/Speed sensor and it's wiring in the rear differential, correct?

 

[mhuitt]

Just to be sure, you checked the ABS/Speed sensor and it's wiring in the rear differential, correct?

I had a mechanic shop check it out three weeks ago (and I fixed everything on the diagnostic) because of this problem. They didn't say anything about any electrical (outside the wheel hub ABS sensor). Do you mean the sensor on top of the rear differential? I replaced that and the one on the transmission in front a few days ago.

Still have the issue.

Would the tone ring be the problem? Or the differential itself? Not a pro mechanic or anything (me and my neighbor fix up what we can on our vehicles) but I am starting to think in that direction (tone ring, differential). And when I took the back sensor off, it dripped a couple drops of what look like water.

But I could live without the speedometer if need be (phones have MPH now on them) but the loss of speed (it seems) when it does that is more my concern.

 

[sgtsandman]

I had a mechanic shop check it out three weeks ago (and I fixed everything on the diagnostic) because of this problem. They didn't say anything about any electrical (outside the wheel hub ABS sensor). Do you mean the sensor on top of the rear differential? I replaced that and the one on the transmission in front a few days ago.

Still have the issue.

Would the tone ring be the problem? Or the differential itself? Not a pro mechanic or anything (me and my neighbor fix up what we can on our vehicles) but I am starting to think in that direction (tone ring, differential). And when I took the back sensor off, it dripped a couple drops of what look like water.

But I could live without the speedometer if need be (phones have MPH now on them) but the loss of speed (it seems) when it does that is more my concern.

Yes, the sensor on the top of the differential. From what I understand, from 1998 until 2009, speed was picked up from that sensor as well as performing an ABS sensor. At least that is how my 1998 Ranger was setup.

An issue with the tone ring in the differential would not be a common problem, but not impossible either. I can't think of a reason something would happen with the tone ring unless something in the differential failed and flung chunks around, like ring or pinion teeth or spider gears breaking.

From what you are describing, if it was a problem with the tone ring, it would be all the time and not after a few minutes of driving.

If the shop did their due diligence, and nothing is wrong electrically, unless there is something in the PCM or one of the other modules, it leads me to there being an issue with the instrument cluster. Cracked solder, broken wires, a defect in the circuit board, or the speedometer itself is failing after it has some time to warm up. Heat expansion could be causing something to open up. With fine electronics, it doesn't take much. I don't know if the speed signal is a direct feed to the instrument cluster or not. A wiring diagram would provide that answer. Unfortunately, the book for my 2011 would not being any help since the system is different in it.