2004 Buick Park Avenue Antilock Brakes engaging when turnin

I had a new rack installed at the recommendation of my mechanic about a year ago. I noticed that the antilock brakes engage when turning and when the stability system turns on. My mechanic could find nothing wrong, and the dealer can't seem to fix it either. I have been back 4 times now and he is now telling me that the rack must be a GM rack. I am at my wit;s end. Is it possible that you can't put a third party rack on GM cars? Got any ideas why this is occurrring. No error codes are registering either.