How do I trouble shoot the RWAL system to find out what's wrong with it?

 

Make sure you don't have a pin hole in the brake line running to the rear end . Other that, replace the the sensor thats on top/middle of the rear housing.

 

yea its called a wheel speed sensor, one bolt and pop it up and out.

 

Actually it's called a RWAL. Rear Wheel Anti Lock sensor.

 

I agree with ryan and zman. I had the same problem. ABS light and speedo would only work above 40 mph.

Changed out the RWAL, and the problem went away.

Just don't do what I did, though. My truck has a clip that the rear brake line runs through, that is held by the stud that holds the RWAL as well. While trying to loosen the nut on top, it twisted the brake line just enough to break it.

I was not impressed, let me tell you.