All of my brake lights on the dash are on but my brakes are fine?

Posted by thesoundofpetrichor@reddit | askcarguys | View on Reddit | 4 comments

2008 Scion XB. 190k miles. I'm the second owner and the past 30k miles were me. It was well maintained by the previous owner and is well maintained currently.

My dad is a car mechanic so I can easily fix whatever is wrong for free, but he and I are both stumped on what the issue is, so I thought I'd ask here and see if anyone else has an idea.

Last week my brake lights came on while I was driving, this was the tail end of a \~2,000 mile trip and I was on my last 50 miles back home of what was 750 miles of driving that day.

I was on the highway and did not use my brakes when they came on so I'm not sure what triggered it. Specifically: ABS, Brake, Traction Control, and VSC OFF (flashing). I pulled into a gas station to see what the issue was, and then the CEL came on 15 minutes after the brake lights came on. The brake lights went away an hour later (while I was still parked at the gas station) and the CEL went away the next day. I ran the codes for the CEL and it was likely the hole rusted in my exhaust (I know, I'm going to replace it as soon as it stops snowing) since it ran system too lean and is unrelated to my brakes, but they did come on around the same time which is confusing.

The brake lights came on again yesterday, same situation, I was on the highway and did not use my brakes when they turned on, but the CEL did not come back.

My brakes work. I just replaced the rear brakes and calipers about 3,000 miles ago and the front brakes are fine, so there's nothing wrong with my brakes themselves. My brake fluid is full. All other fluids are at normal levels.

My cruise control also stopped working a few months ago if that's relevant. This makes me think it could be the brake light switch, but the cruise control was intermittently going out for months and stopped working entirely in November, while the lights on my dash showed up last week so I'm not sure they're related.

I replaced the cruise control switch and that didn't fix it, so I was going to try replacing the clock spring, but the brake light switch would be a lot cheaper to replace.

What could possibly be going on here?