Like the title says I have a 88 firebird and the multifunction switch does not operate the windshield wipers. If I hold down the spray/mist button the wipers do work but this is annoying and leaves only one hand free. Does anyone have this issue as well? I know it can't be the wiper motor, it has to be something uncooked or shorted out somewhere, but why would the work with the spray button?

 

Have you tested for power to the motor? A lot of times the very tiny wires in the multi function switch break after years of being used. Then you need a new one. That's what mine did