Near the end of the episode, after K.I.T.T. reflects the laser into K.A.R.R.'s scanner, the two cars go head to head turbo boosting at one another. But K.A.R.R. was programmed for self preservation, it should have never done that
When the laser bounced back and hit KARR's scanner, it burnt out held of his circuits so he wouldn't have the program for self preservation and would just turn into a killing machine. Plus, he also said "if I am destroyed, so shall you be"