Anyone know why brake lights would light up but not become brighter when the brakes are touched? They shut off when the lights are off, but will light up and not brighten when the lights are on.

You could have the wrong bulbs with one filament instead of two.

They both have two filaments. Theres a thirdbrake only light above in the back that doesn't seem to work at all, I wonder if they are all connected.

More details: are you meaning the small filament(tail light)in the bulb will work when you pull the headlight switch out one click but the large filament in the same bulb(which is for the brake/turn signal/e flashers) wont light up when you hit the brakes.

RapidRobert, yeah that's the problem, and it looks like both filaments are ok (I haven't tried replacing them with new bulbs, working on that now)

(1) check the fuse box & see if brake fuse is Ok then see if the brake pedal switch has 12V to it(most likely does)and if the switch there is closing(most likely is) but it's always a good plan to progress downhill & not assume anything then pull the harness apart at the steering col(the harness that has the brake/turn sig wiring)not the ign switch one & with the white/pink connected at the brake pedal switch see if the column harmess is getting fire then there's 2 wires in that same harness that would send fire back out to each of the rear brake lights,see if they are both getting power & if not(the most likely culprit)(the turn signal switch), but if still getting power continue rearward as there are one or 2 connectors from there to the bulbs at the rear of the car. The bulb sockets not grounded good is a possibility but since none of the brake light are working nor is the 3rd brake light & it's not feeding back thru the small(park lights) filaments I'm suspecting the power side