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Thanks, Kev.

Here is a bit more information on what’s happening. Most of the time things seem to work fine. Then, on occasion and seemingly no reason (like in the middle of the night), the brake lights will come on dimmly (sometimes brighter than other times). They were definitely off before and then just came on at some point. Now, these are LED bulbs, so it doesn’t take much to make that happen. But, the car was just sitting and cool.

Initially, I could tap the brake pedal and that would normally get the lights to turn off. The problem has gotten progressively worse and happening more often. And, tapping the brake pedal has less and less effect of turning off the lights.

I’m wondering if the diaphragm in the switch has weakened and not “springing” back to the off position as it should. It seems like that could explain the problem getting progressively worse.

I have no idea when/if the switch has ever been replaced. Anyway, that seems like the place to start.

I have new coil springs to install, and looking at the shop manual, it looks like I need to disconnect my brake lines as part of the spring removal process. I’ll likely replace the switch at the same time so I only have to bleed the system once. Then again, depending on my brother-in-law’s (mechanic) schedule for help with the springs, I may go ahead and do the switch first and then bleed the system again when we can get to the springs.

Some master cylinders are designed to keep a small residual pressure on the system to keep the cups set and prevent air intrusion. Maybe your brake light switch is too sensitive. Or maybe a small amount of current is leaking through the switch due to brake fluid getting on the contact side of the diaphragm. Brake fluid often has some moisture and fine rust in it, which could aggravate leakage.The Led lights might respond to a very low leakage current that would not affect regular filament bulbs. I'd disconnect the switch and see if the problem goes away, or replace it.

Replace the swtich. $12.99 Napa. SL-134

Or if you want screw style terminals: