I have a '94 Ranger 2wd, 3.0, with the RABS, just found out it was there, that has never worked as far as I can tell. My truck has 256,478 miles on it and all I have had to replace is the front brack lines, rotors and bearings, water pump and alternater. I found a leak of brake fluid by the rear left tire and belived it was just a line, so as a DIY'er, I cut the end of the line off bythe rear hose connector and the line at the master cylinder, I protected both with plastic. I then started looking at the book and discovered the RABS unit and went to check, It's there! Never had a sense that there was ABS on my truck, it never acted like it. So, now I have to replace 2 lines. Do I need to bleed the line between the master cylinder and the RABS first then the rear drums or can I connect everything and use a recovery method and bleed the lines at the rear cylinders ad get good results?

 

I'm not sure how the internals of the RABS valve work, but I do know that during normal brake bleeding, the system behaves just like the valve isn't there. You should be able to bleed the entire system just like any vehicle without ABS. The valve responds to commands from a controller mounted under the dash. The controller receives skid info from a single sensor mounted on top of the rear differential. From what I've read, most failures come from a dirty or failed sensor, which is cheap and easy to replace. My experience was I had contaminated fluid, which froze the RABS valve closed with rust. I had zero brake pressure to the rear wheels (even with the bleeders open and someone pressing on the pedal).

In your situation, I'd replace/repair your lines, and then bleed/flush the entire system using standard procedures. Then, just for fun, I'd check the sensor and wipe off any crud that might be on the end of it. The RABS system won't behave like a 4 wheel ABS system. There's no pulsing pedal or growling noise. The RABS valve will only dump brake fluid pressure (to the rear wheels only) in a skid condition.

If you've got what I had...no fluid getting to the rear wheels at all (you'll discover this during brake bleeding if your truck is doing this)...let me know. That's another long story.....

 

The rear ABS on these trucks is pretty useless- about the only times I've felt it when I wasn't trying really hard to get it to engage is the first hard stop on a rainy day after I get my studded snows mounted in the fall. Even then, I usually feel the rear tires locking and ease off before the ABS gets around to doing anything...

 

Ya I've rarely noticed mine kick in, but when it does its pretty obvious even w/o the pulsing pedal. Your rear brakes may have even been so far out of adjustment that they barely did any braking to begin with, there for if the rear axle never stops rotating, no RABS!