I had to brake really abruptly today and pretty hard on the way to work today. The Brake failure light came on afterwards but very very dimly. It is braking fine and it seems like the light goes off every so often. The fluid level is good and I bled the brakes less that a year ago. What should I check?

This is what's inside it. Dim probably means the switch isn't making good contact. My experience is with the light coming on (dimmer than it is during lamp test) because the combination of water, brake fluid, and rust inside the switch cavity passes enough current without the switch even making contacts. The fix, for me, is to remove the switch and clean it out with solvent and swabs. Getting the switch to thread back in can be a real pain if rust has grown around the opening.









--
Art Benstein near Baltimore

Be careful about reading health books. You may die of a misprint. - Mark Twain

Wow Art, that is awesome. I drove it about 50 miles today and it went off but I don't like the idea that it is failing.

Fix for me is too pull the connector off the octopus and tape it up as the rust on it will make it impossible to correct and reassemble.

"Fix for me is too pull the connector off the octopus and tape it up as the rust on it will make it impossible to correct and reassemble. "

That will work, and the black tape is more effective there than on the instrument panel.

If you work on cars other than those only you drive, you might try the sharp flutes of a pipe thread tap used as a scraper. I did not have the correct tap to chase the rust out, but with persistence was able to use just the edges of a smaller one. Good neck strengthening exercise, if I recall.
--
Art Benstein near Baltimore

By all means, marry. If you get a good wife, you'll become happy; if you get a bad one, you'll become a philosopher. - Socrates

Art my octopus is so rusty all the flare nut ends on the lines are severely degraded to the point of being rounded without ever being touched. I actually had to apply undercoating to it to prevent further decay on my 88 daily driver here in NJ.

Yup. Rust is a word with as many meanings as there are pairs of eyes or parts of the world. Makes me glad the lines themselves are not made of steel.
--
Art Benstein near Baltimore

People who live on that "New Car Smell" and have their Credit Score memorized better than their own birthday will ALWAYS say you're Crazy. -punk240 Tim

Its makes no sense that manufacturers are still using steel lines for brakes. But I guess its a moneymaker down the road.

If y'all are tired of fighting rust you need to move down south. (Besides, the summers are lovely - NOT!!)

Yeah no thanks. 4 seasons here in NJ

https://www.eeuroparts.com/Parts/4105/Brake-Proportioning-Valve-1273052/

this is the source of your light.
this valve attempts to ensure brake fluid pressure is even from drive to passenger side.
your hard braking moved off center and to one side more than the other a spring loaded plunger within this valve.

live with it for a bit and see if it re-centers itself