What film does Steve Martin look at a motorway sign for advice?

There was a film with Steve Martin in that I saw as a kid and I remember him going to a motorway sign for advice or messages or something along those lines. Can anyone help?|||It was definately LA Story:-





Steve Martin is Harris Telemacher, a wacky television weatherman, who thinks his life is perfect, except for an erratic relationship with a style-conscious girlfriend (Marilu Henner). Then, one bright and smoggy L.A. day, an electronic freeway sign changes his life, when its advice leads him into a frivolous romance with a young and beautiful blonde (Sarah Jessica Parker) and, ultimately, to true love with the woman of his dreams (Victoria Tennant). Set against the backdrop of Los Angeles, it's the most hilariously romantic L.A. story you'll ever experience.





Hope this helps.|||I'm guessing it might be Trains, Planes and Automobiles but with my luck at the moment, I am almost certainly going to be wrong!|||L.A. Story|||L.A. Story ... brilliant comedy by Steve Martin|||L.A Story|||First I thought it might be The Jerk, but LA Story sounds more plausible