I was on the interstate doing about 75 mph in the left lane coming up on a on ramp with a semi and other vehicles behind him trying to get on the interstate. All of a sudden a guy in a Pickup shoot over into the left lane the guy in front of me locks em up I have to do the same slowing down to like 30 mph and looking for an escape path. Once I get rolling again I notice my ABS light is on and it stays on all the way home. I get home and turn off the truck and then turn it back on light is still on. I have a CTS2 so I check for a code there isn't one. Looking for some ideas on how to diagnose the problem.