Electrical Issue 99 Taco

Folks, wrap you big brains around this: a few weeks ago, brakelights started failing in a weird way in the 99 Tacoma. With the engine off, one day I noticed if I applied the brake pedal (like I normally do right before starting up) the "Headlights Still On" chime would happen. So I did a light check, and as it happens the brake lights wouldn't work independently of the headlights IF the headlights were turned on; they just stayed on full blast, and didn't brighten to let indicate that the car was braking. Not good, obviously.


Internet says check the brake/stop lights switch. Did. that. It wasn't the issue. Ditto with the multifunction switch. Stepdad is a master MARINE electrician but we can't figure it out. Checked: fuses, relays, and all bulbs and sockets. Tomorrow, I'm jacking it up and checking grounds for corrosion but not optimistic.


You ever heard of or encountered anything like this? Any suggestions come to mind, holler. Thank y’all in advance for any suggestions.

 

Wow. That is a first. I am completely flabbergasted on that.

 

With the headlights ON, are the brake lights On or Off?
If you pull the STOP fuse, does the "Headlight on" Chime still go off when you press the brake pedal?

We need to isolate the problem.

Bad grounds can cause WEIRD issues.

I think we can figure this out. Just need to start isolating circuits and connections.

With the headlights on, does the brake light on the back of the cab come on?
What if you press the brake pedal? does it then?