ah yes thats the solid state intermittant wiper module
I had mine finally go out after 270K miles, it was a ***** to diagnose what the problem was because I did not know that sucker existed until I traced the wires under the dash.
I went to the junk yard and pulled about 8 of them for spares, I plan to keep my BII forever.....
I wouldnt worry about it in a prerunner, my BII has been jumped, dropped, bounced around all over the place and that sucker still worked fine, its just old age that killed mine....