Is there a wiper motor pulse board on 1989 Suburban?

No, a 1989 Chevrolet Suburban does not use a wiper motor pulse board in the same way that some later vehicles do. The wiper system in that year's Suburban is controlled by a simpler setup, typically using a switch that sends power directly to the motor, and perhaps a resistor for different speeds. There isn't a separate dedicated printed circuit board (PCB) or module specifically called a "pulse board" to control the wiper motor's operation. The control is more directly wired and less sophisticated than those using electronic controllers that would have a pulse board.