I'm curious why the Shift Interlock system would affect the ignition key switch anyway. There's no electrical solenoid in the steering column associated with the ignition switch that actually locks the key in place until certain conditions are met as far as I can see in our repair manuals. Did I just not find it? Has anyone who has ever replaced their ignition switch noticed any sort of additional mechanical linkage that runs from the transmission shifter to the ignition switch in the steering column?