Upper brake light working (above rear window), but two lower lights not working. replaced fuse and bulbs. still not working. 2001 chevy astro van

Tony, our TB's only have 3 bulbs, 1 brake, 1 running, 1 backup.
If you happened to be playing with NEW LED bulbs (from local retail location) for the brakes, guaranteed you blew the fuse under the rear seat. It takes a special CK socket for the brakes that no one carry's. If you're only dealing with normal incondecent bulbs, I'd still check the fuse under the rear passenger seat.

Buy a cheap multimeter and measure your voltage at the bulb when the brake lights are supposed to be on. You should have 12vdc. Is your 3rd brake light and brake lights on the same fuse? If not, measure to see if you have 12vdc at the fuse itself.

The power for the data link connector is from a 25amp fuse Number 7 in the IP fuse box. As long as the check engine light is on the computer has power.
The main computer power is from two ECM fuses in the box near the battery.
The fuse locations should be in the back of your owners manual.

Check the tail light fuse and check the bulbs. most likely have dual element bulbs so make sure both are good.

Fuse or short. If both went out then a short. Check brake pedal assembly wiring from there back to lights. If lights stayed on then it's the button assembly (physical) that's apart of the pedal assembly but that's not the case if off altogether. I had MANY shorts with the Astros I've owned although I do love Astros.

You have to remove the upper applique to remove the tail lamp, it is the trim panel above the lamp. I think it is held in place by two nuts/bolts but not sure. You have to have the rear doors open to remove it

well u have two seprate problems the hazards and turn signals have a flasher that needs replacing if the fuse is good on the fuse box marked signals .and there is a brake light switch under the dash board near the brake pedal it has two wires on it check the wires make sure they are connected if so replace the brake light switch

Fuses are located up under driver side near brake pedal it has a pull down cover over them.

theirs a sensor for the abs light have that replaced the shop should've advise you of that.

Check the ground wire & leads, if not try the multi-function switch in the column