77 CDV, 06 DTS III, 69 FWB
They so, using a fiber optic cable like the ones the lamp monitors use. The cable runs from the thermometer housing and follows the wires that power the windows and such through into the passenger compartment, then up behind the dash, where it terminates at the bulb house for either the light controls or the wipers. There is a small metal retainer that holds the end of the fiber cable in place, so make sure you get the bulb socket from the doner car if you're retrofitting the option onto your car. Make sure the ends of the fiber cable are clean for best illumination.