Let's start with where are you, and then follow that with what vehicle are you driving? 98 was a changeover year for Suzuki and your 98 Vitara could be either an SE series or an SQ series.
On the SQ series the wiper motor is located directly behind the battery - there is a 4 pin connector between the motor that is susceptible to corrosion damage from battery acid, and will cause the symptoms you describe.
98 - 1.8 Mitsubishi Pajero iO
98 - 2.0 Suzuki Grand Vitara