So, after momentarily tapping an aftermarket boost control switch into the button illumination + voltage wire to the headlight lift switch, I have no panel illumination, no cruise, and no horn. I have not dug into the issue deeply, but all the fuses are fine, and I've already replaced the dimmer switch. Next replacement is the panel light control module behind the speedo. Anything else I should try before I take an entire day going through the wiring diagrams and tracing wires on the car? Is there a fusible link I'm not seeing on that circuit?