On my '82 the wipers would not shut off/ not work as pulse so I replaced the assembly/circiut board. This fixed the problem until I started the engine which left the pulse working randomly but they will shut off. Thought may be a faulty part so tried another one. Work fine with engine off. Same thing when engine on only it seems the do work more than less this time. Could this be the switch in the column. Not sure if I remember correctly, but is there a different assemblies for earlier/later cars?