I recently installed a new turn signal wiring harness in the steering column because my horn would not work. I found the original turn signal cam was broken and it looked as though a short had occurred sometime in the past. I reinstalled the steering wheel and the horn worked again. However, while taking the mustang out for a drive, I noticed that when I would make a turn, the turn signal canceling cam now contacted the turn signal cam causing it to click back and forth. The canceling portion works fine but the turn signal lever now moves up and down with any turn. I'm thinking the replacement part rides a little higher in the steering column. I could try grinding a little off the two prongs that stick out or just live with it except it's kind of annoying. Hope this all makes sense.

 

Did you figure it out? I have a similar problem and my reasoning is the same as yours. I have an aftermarket wheel. Is yours stock?

 

Haven't figured it out yet but am looking at buying a Scott Drake turn signal wire harness. I'm hoping the better quality takes care of the issue. I think the steering wheel is stock but am not sure. I'll look into it. I didn't have this problem before with the turn signal. Just wanted to get my horn working again which it is but now have this new issue.