Brake lights just quit on my 87 TII.

All the bulbs are fine, the fuse is fine (replaced it to be 100000% sure, but the old one was fine) - all the other lights work fine. I disconnected the switch and jumped the wires, still no lights. The grounds at the back of the car are fine, and I redid the underhood ones in the summer.

What should I check next?

 

getting 12V to the green/white wire at the switch connector?

from there it is fed from the 20a tail fuse in the cabin, before that the 60a fuse in the engine bay. it's about one of the simplest circuits on the car, so long as the fuses are good then jumping that switch should have worked so i bet you have one of the 2 fuses blown.

 

both those fuses are good. Batteries in my multimeter are dead and it's a holiday today so I can't check for voltage easily until tomorrow. But I'll check that next.

I did some more poking around and I think the brake light signal actually runs through the CPU so I'm going to have a look at it if everything else seems fine.

 

it does, after the switch. if there's voltage at the green/white wire but not at the tails then the next place i would check is the connections at the CPU.