I have a 1998 Dodge Ram 4x2. Now when I first start it up the ABS and brake light comes on. If I let the truck run for 30 seconds and turn it off and then turn it back on the lights don't come back on. What is the problem?

 

The wheel speed sensor is most definately your problem. I had the exact same problem with my truck. It sits on top of the rear differential, theres i think a nut you have to remove to remove a covering bracket and then another bolt to remove to get the sensor out, I had to swist and contort mine until it came out. It was i think 35 dollars at auto zone, put it in and it fixed the problem... Try that, if the problem doesn't get fixed, you can always bring back the sensor and get your money back.