I have a Toyota Celica AT160 and the brake system warning light is off when I start the car, then after a few seconds it comes on.

Car info:

Toyota Celica AT160 1989 Engine 4AGE No ABS

Things I noticed/checked so far:

  1. It’s not the parking brake switch I’ve confirmed that.

  2. Recently my brakes went poof while on the road. Fortunately I was able to stop. I went to the side and noticed that my brake fluid level was low. Luckily I had some in the back of the car topped it off and build up pressure and was able to make it home.

  3. When I got home upon inspection I noticed a small tiny leak on the rear right side of a car. The next day I fixed that, I just cleaned the threads of the flare nut and tighten it snug. Since then i have no leaks.

  4. I bled the car and I now have normal breaking pressure and the brakes perform as expected yet the issue still persists. it was a b.itch to bleed, I’ll tell you that.

  5. I also noticed that when i pump the brake pedal, the car’s idle RPM goes slightly up. This let me to believe that maybe my master/brake booster is failing.

(The reasoning behind this is, that if the master or brake booster are failing internally whenever I press the pedal, there would be a small vacuum leak in the membrane allowing unmetered air to enter the engine.)

To check, I disconnected the vacuum hose from the brake booster, plugged it and proceeded to press the pedal while the car was running. It did the same thing (revs increased slightly).

When I removed the hose to get a baseline of what the car would behave like if there was a vacuum leak the car revved way higher.

  1. The weird thing about this is that whenever I break hard the light turns off, but then comes on after a few seconds.

Additional info

  1. I doubt it’s a sensor malfunction because my brakes did fail on me.

  2. I also installed new brake hoses 6 months ago.

  3. Brake fluids were new and the car’s braking system was properly bled before.

  4. I don’t notice The driver’s side carpet be damp, which would indicate that my master is leaking.

I am stumped and out of leads so any input is much appreciated.

  • conspiracy_troll@alien.topBEnglish
    1·
    1 year ago

    I’m a backyard mechanic, no answers, commenting to see if you find out what it is. My guess is air in the line somewhere or vacuum leak somewhere. Hope you get an answer!

  • RudbeckiaIS@alien.topBEnglish
    1·
    1 year ago

    Brake warning light going off while braking is a symptom there’s something wrong with the sensor float.

    Advics master cylinder are notorious for leaking inside the brake booster: start from there.