Check Brake Light 2010 Mitsubishi Outlander ES

Hi everyone! On three separate occasions, while driving, my check brake warning light has come on. When I brake, it immediately turns back off. On the second occasion it came back on about a minute later, but again, turned right back off after pressing the brake. There is no rhyme or reason to when this happens–the first time I was going about 25mph, the next two times it happened on the highway when I was going 55. It has happened within a couple of minutes of starting up, or after about 15 minutes. I haven’t driven it for further than about 20 miles since it started, so I can’t speak to whether it continues to occur on long drives or not. Sometimes it doesn’t happen at all.

I haven’t experienced any difference in braking–same amount of pressure when I press the pedal, same stopping distances, no vibrations or noises, etc. It was also recently at the shop for an oil change and tire rotation. The car is about 2.5-3 years old and has 20,600 miles on it (I don’t drive much!). I checked the brake fluid; it is smack dab in the middle of the min and max lines, and it is clean. It was also just in over Christmas for the big 2 year/30,000 mile check and everything was totally fine.

Any idea what this could be?

Not sure what the brake light indicates on your truck but often it is related to fluid level so check your manual. The level is sensed with a float in the brake reservoir. “Min” really means the absolute minimum level required for your brakes to work properly. The warning light may very well be tripped earlier. The level having dropped some may mean that your brakes are starting to wear.
I’d add a little brake fluid to see whether it goes away.

Thanks! I called the mechanic too–he said that sometimes those systems can be fussy. Even though it’s not low at all (between min and max fill lines), if the fluid moves back while driving it will register as too low, and pressing on the brake will push it back up above it making the message go away? Or something like that. He recommended adding more brake fluid and seeing if that fixes it as well. They didn’t notice any wear on the brakes that would warrant them needed to replaced yet, so his over-the-phone guess was brake fluid or electrical fault (the two options listed by the manual as well).

Added more brake fluid tonight–we’ll see how it goes!

Thanks for getting back to us. Fluid will drop over time because, every time you use the brake, your pad wears a little. It is miniscule, but the pad loses a little thickness every time. That difference in thickness is made up for by the fluid of the brake system - causing the level in the reservoir to drop a little.
That’s all perfectly normal. Nothing to worry about unless you suddenly lose a lot of fluid. That’s why it is always a good idea to look under the hood periodically to make sure the level is normal.

It could be that the sensor in that tank is acting weird but let’s hope it is just the level. That’s a cheap fix.

Let us know how you make out. Knowing what caused it may help someone else.

I wouldn’t have recommended adding brake fluid if it is in the middle between high and low. The reason is that the way most brake systems are designed, the level in the plastic bottle gives the owner an indication of brake pad wear. If it is in the middle, that likely means the pads are about 1/2 worn out. So you get some heads-up on when you need to install new pads. When you add fluid, you loose this calibration. Also, you make the process of replacing the pads more difficult.

I guess if adding brake fluid fixes the problem, good on you. But I don’t think it will. There is probably something else wrong. If you have Anti-lock brakes (ABS), my first guess would be a problem with a wheel speed sensor. Otherwise, it could be a faulty master cylinder, brake pressure/balance sensor, or caliper.

I always keep my level topped off to minimize the column of air in the reservoir. Brake fluid is hygroscopic so attracts moisture when it can, including that column of air that is steadily growing. It minimizes the risk of water/air in the system.
A turkey baster sucks it back out when I push the caliper back in. No biggie.

Most cars have separate ABS and Brake lights. Brake lights usually indicate a dropping level.
His truck may be different, though.

It is not the ABS. I’m fairly certain that’s an entirely different warning light, if I’m remembering my manual correctly.

The mechanic on the phone said since the fluid wasn’t low, they probably didn’t top it off, no one thinking that the sensor might be overly fussy. I’ve driven it every day since adding a bit more fluid–in fact, driving it more than I usually do this week–and have had no lights come on so far, so it seems to have fixed the problem (knock on wood).

I’d like to reiterate–I have had no change whatsoever in my braking experiences. No noises, no shimmying, the steering wheel doesn’t shake, braking distance seems the same, the brakes aren’t mushy, etc. Plus the light comes on only when I’m NOT braking, and then immediately goes away when I put pressure on the brakes. All of this is what led the mechanic to believe it’s an overzealous sensor that likes the reservoir to be pretty full, though very likely there is nothing wrong when the message comes on as long as there is enough fluid in the reservoir.

Thanks again, everyone!

No problem. Glad it isn’t anything expensive.

Just remember that your brakes will likely need service in the not too distant future. The pads may have an alarm tab that will start to whine when it is due but don’t let it go overdue as that gets more expensive.

My 99 Camry brake light comes on if it senses a bad stop lamp, either at the rear or on rear window. Could it be the Parking brake switch?