Did a search for this and found some similar subjects, however a couple questions not answered. I have 99 Ram 1500, 4x4 with the ABS and E-brake light staying on and the cruise control not setting, the green light will come on when turned on, but not set. Less than 18,000 miles and 2 years ago the rear speed sensor was replaced. Called the service center where work was done and getting, I feel, something of a run around. The service guy says he doesn't know my truck very well and there could be a left and right rear sensor and doesn't know which one exactly was replaced. Not able to give me a good answer without me bringing the truck in for a diagnostic. During the search here reading there is a differential sensor and a tranny sensor. Should I take it in and spend the $120 or replace the sensors (which one)?

 

There should only be one rear wheel speed sensor and it should be located on the top of the diff. If your rear speed sensor is bad your speedo. will be inop. at low speeds(0-30mph). If your speedo works all the time it might be a good idea to go ahead and pay to have it diagnosed.