f 150 abs light stays on

Just have to have the vehicle scanned for ABS codes. You can get it done at a auto parts store. Write down the codes. The codes will let you know where to look, and what to look for to repair.

About all you can do as a lay person is to clean the sensor on each wheel. It is possible the sensor has been caked with dirt and gunk. Hosing them off could do the trick. Check the net for a how-to video.