[LHaven]

The range and oven work entirely off propane and piezo... except for the oven light, assuming you have one, which would be 12v and therefore fused. That should be the only intersection of oven and fusebox. It's beginning to sound like you had some piece of physical detritus that somehow shorted the oven temperature knob to the light circuit. I might be able to arrange this with a shish-ka-bob skewer if I were very clever.

I'd take off the range cover and examine the behind-the-knobs area for smoke tracks.