[V8] HVAC head lights

[Kneale Brownson]

I replaced the melted plastic part to the headlights connector, including
cleaning off the stud on the switch and splicing in a piece of wire with an
appropriate end for the connector that didn't have contamination from the
melted plastic.  I'd replace the switch assembly itself when I first
discovered the problem, followed almost immediately by the relaying of the
headlights.  However, occasionally when switching from high to low beams,
the lows would not go on, so I figured it was a poor connection
contaminated by the plastic that melted into it.

Anyway, now everything works as normal except when I turn on the lights,
the lights for the HVAC controls go out.  I'm sure my bride won't like that
 :~).  This is V8 #1 which is supposed to be her car.

So what did I disturb?  What triggers the dimming of the dash lights and
why does it now only turn off the HVAC (and, thinking about it just now,
possibly the radio) lights?