You need to have the ABS codes read. That will tell you what is going on and and lead you in the direction of getting it fixed. Some auto parts stores can read ABS codes, but you might need to take it to a shop to have it done.
i am the same way, and had the same problem i took it to my local dealer and they replaced the abs module. Picked up the truck from the dealer, started going to work when about 20 milles on the road bam!!!! The abs light comes on.. Called the dealer told them i was going to take it again the next day, my neighbor is a ase certified mechanic and he told me that it could be the ecm module. So the next day i took it told them to check the ecm module and that was the problem. Its been about a year and the light has not come on!!!!i tried the search function but didn't come up with anything so bear with me. Anyways, a few weeks ago i was driving and my abs/brake light came on. It turned on and i heard the dinging sound. Then it went off. It continued to cycle on and off every few minutes for a while. I turned off the truck,and the next morning it didn't come on for the first half of the day. Then suddenly it started doing it again. Finally, after about a week or so of the same thing, the lights finally just stayed on all the time. Now when i start the truck, the lights automatically come on, including the dinging sound which is very annoying. I checked the fluid levels on the brakes, and it's fine. The brakes work fine, so i have no clue where to begin. It is rather annoying and would like to get it fixed. Any ideas? Oh, and sometimes when i start the truck the abs light comes on automatically and the brake light will come on about 2 seconds later. The annoying part is the dinging. I think i might have a small case of ocd and i can't stand the lights on in the truck. I'm a perfectionist and i like to have my things working fine, and this is really bugging me. I need someone's help! Anyone have this happen to them, or know what could be wrong?