After driving through some nice downpours, I've been getting the usual "Bulb Failure" light, but this time it appears that the problem isn't a leaky tail light cluster.

A few days ago, I did blow out a bulb in the tail lights, but I've drilled a hole in that panel, replaced the bulb, and now that light, along with all of the other brake lights, are working as they should be.

My problem is that the interior driving lights--the dash illumination lights, the 52mm clock light, the lights behind the center and shift console--turn on when I brake, even with the headlights off! At the same time the "Bulb Failure" light comes on in the dash. Here's a breakdown of what causes the light:

Headlights off, brakes off--no warning light, no interior lights (normal operation)
Headlights off, brakes on--warning light, interior lights
Headlights on, brakes off--warning light, interior lights (normal operation of interior lights)
Headlights on, brakes on--no warning light, interior lights (normal operation)

Does anyone know what kind of electrical problem I have and how I can fix it? It sounds like a wire relating to the interior lights with the headlights got crossed with the brake light wiring.
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'89 244 GL -- 105,XXX miles (see profile for info on car)