Brightness knob
 

Hi!

I recently bought a (very) used 2004 Isuzu Ascender (2wd, 4.2L L6 engine). Why does the Instrument panel brightness knob push in and out? I've clicked in in, and it stays in, then push it again and it stays out (extended)? Turning it changes the instrument brightness whether it's in or out, but pushing the knob in, or out, seems to do nothing. Anyone know?

Not knowing is kinda driving me crazy. (even the "dealer" doesn't seem to know.)

Thanks!