What do you hook the dimmer illumination wire to?

The dimmer illumination wire is typically connected to the vehicle's dashboard lighting circuit. This allows the dimmer switch to adjust the brightness of the dashboard lights in conjunction with the vehicle's headlight settings. In many cases, it should be connected to the same wire that powers the other dashboard lights, often identified by a specific color code in the vehicle's wiring diagram. Always refer to the vehicle's manual or wiring schematic for accurate connections.