My '98 Ram 1500 5.9L 4X4 has it's ABS/BRAKE light on. Now from previous posts I have read here it appears to be the speed sensor. Now just the other day my speedo is starting to act up as well, so another indication that it's the speed sensor. Now here's the question - WHICH sensor should it be, the one on the rear diff or the one on the trans???? From what I have read in other posts it seems to be a 50/50 in which one fixed the problems. I would sure hope to replace the right one the first time and not have to end up replacing both of them. I like so many others out there, I hate to spend more money on repairs than I need to, so I sure hope this wonderful forum can tell me for sure the right one to replace. So PLEASE HELP! Thanks in advance.

 

8 out of 10 times, when you have those lights on it is the sensor in the rear diff. The speedo could be a seperate problem.

 

But if I read right in another posting here, the speedo is also controlled by the speed sensor. If this is so, which one? It's fine about 20mph but once you slow down to that speed it drops right to zero.

 

It's the speed sensor located on top of the differential...

I had EXACTLY the same problem. Replaced it and no more problems with the ABS and BRAKE indicator lights, and it fixed the speedometer problem!!