Replaced with new dimmer/turn signal switch but still no dims. help!

clean conections inside stering colume

From the post i'll assume that the High beams and other running lights work.
I would start at the headlamp plugs and work my way toward the fusebox. theres a fuse or fusable link and a relay in the headlamp circuit that you should find and check. I'm sorry, that I don't know the location of those on a '88.