1988 Silverado brake lights stay on at all times. Even after disconnecting the brake switch. Any ideas?

you probably need to look at the wires good down by the brake pedal,,and make sure one isn't pinched or grounding out,,i had an s-10 do this exact thing on me,,i do this for a living,,so i have seen a few of them like this i had one that worked all the time even after we put a new switch on it,,it had a bare spot in the wires,,about 4 inches up on the wire,,as if someone had actually cut them in it,,the only other thing that will cause this is the turn signal switch,,all you rear light,s including your park,,and running light,s run through this switch,,when they go bad they will drive you nuts trying to repair the problems they cause,,you have to pull the steering wheel to replace it,,it takes a few hours to do,,if all else fails,,you may have to replace it,,i hope this help,s

on that year model, chevrolet had a bad problem of the brake switch being miss adjusted. But since you say that it stays on after you unplug it, leads me to believe you have a short-to-power in your brake wire. Easy way to figure out which circuit it's shorted to, is to start pulling fuses out one at a time until brake light goes off. once you've found the circuit, try and figure out what the circuit powers up and then trace the wire back to your lights. 9 times out of 10 you'll find the short near a bend or a place that the wires are rubbing up on. That's about all I can give you without seeing the vehicle, hope this helps

sounds like you have a wire from the brake lights going to Ground, trace out the wires from both lights all the way to your switch, also check out the lamp sockets for shorts. I suggest that you use an short checker, the one with a probe , a ground clip and a light in the handle, they are cheep and well worth the couple of dollars, save you a lot of time

Warning of a malfunction of the master brake cylinder...have it checked out asap

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