"Trust Doesn't Rust" - Season 1, Episode 9Edit
Once KITT was constructed, it was presumed that his prototype KARR (voiced by Peter Cullen) had been deactivated and dismantled. However, the latter did not occur and KARR was placed in storage and forgotten following the death of Wilton Knight. When two thieves, Tony (Michael MacRae) and The Rev (William Sanderson), break into the warehouse where KARR - who is entirely identical to KITT with the exception of the Yellow/Green Voice Module on his dashboard - is "sleeping", they unwittingly reactivate him, and he escapes.
When the two thieves realize how useful the vehicle could be, they use KARR to go on a crime spree, whilst Michael and KITT frantically try to catch up with KARR and stop him before anyone is seriously hurt. Bonnie devises a high-powered laser, the only known way to stop KARR, which must be fired from KITT directly into KARR's scanner. However, when KARR needs maintenance, Tony kidnaps Bonnie before the laser can fully be calibrated. Although Michael rescues Bonnie, she is unable to get a clear shot at KARR with the laser and he escapes.
KARR's only weakness is his primary directive of self-preservation and Michael uses this to his advantage. When KARR threatens to destroy KITT in a head-on collision, Michael plays chicken with him, on a hunch that KARR will veer out of KITT's path in order to protect himself. KARR indeed swerves out of the way, but unable to stop in time: he drives off a cliff and seemingly explodes in the ocean (using footage of the climactic scene from the 1977 film The Car, footage that was also used for KITT on a couple of other occasions).
Trust Doesn't Rust was also printed in book form, written by Roger Hill and Glen A. Larson, following the story and general script of the original television episode, expanding some areas of the plot and adding several extra secondary characters.[1]