So.. on my 98D, got bpth Brake lite adn ABS lite on all the time. No apparent problems with brakes. Fluid OK, equlization block OK, brakes work good.
Thought ABS lite could be the speed sensor on Diff, but why the BRAKE lite.

Anyone ever replace speed sensor on rear diff ?? How hard ???
How much it cost to buy the thing ???

 

It's most likely the rear wheel speed sensor, $34 from the dealer. Takes 15 min to change. I just did mine, after I was done both lights went off.

 

If the RWSS dosen't fix your problem, you might look at your output shaft sensor located on the drivers side of the transmission tailshaft- I had the same problem as you but found that both of my sensors were bad- which made trouble shooting an interesting proposition. The OSSS cost me abt $23 and made a mess- some transmission fluid will leak out- but took only 10 min to replace.

 

 

The Output shaft speed sensor thing, is this the same thing that causes the eratic shifting and will give check engine lite on failure ??
I had that replaced in the spring to rid the 98D of these symptoms. Interestingly, the rear wheel cyls were bad and I replaces them in August, (easiest wheel cyl I ever did) and while doing that, adjusted the rear brakes. I don't think the rears have ever worked as it appeared the auto adjusters have never moved. Any thoughts ??