Electrical

I have a 1995 Chevrolet camaro and whats wrong is that whenever I start my car the abs inop light comes on, nothing electrical works only one thing at a time and not good, as in when I turn my heaters on the radio will turn off, my headlights wont work nor will my turn signals, I'm thinking it might be a ground wire coming lose but I'm not sure please if you have any idea let me know cause I'm lost