2007 Scion TC brake warning light occasionally flickers

I have a 2007 Scion TC. Sometimes the dashboard brake warning light will turn on for a few seconds and then goes off.

It happens after the brake is pressed at a traffic light or stop sign, a second or two after releasing the brake pedal and accelerating. The sometime the dashboard brake warning light will switch on for a few seconds. It seems to occur more often when the outside temperature is cold. Also when the car is cold. I had a oil change and lube and they said the brake fluid level was ok.

How serious is this?

I suggest checking the brake fluid level.

A flashing brake warning light is often caused by low fluid in the reservoir. When you accelerate or brake the fluid sloshes a little, and this can cause the sensor to illuminate the warning light.

At Jiffy Lube they said the brake fluid level was ok.

Edited to add that the car has 41000 miles.

Jiffy Lube???

You have two problems, cwallach:

Your brake fluid level IS low, more than likely.

You take your car to Jiffy Lube, where the level of incompetence is incredibly high.

If you value your car, you will stop taking it to Jiffy Lube or any other fast lube place.
The kids who work there are not mechanics, have been given VERY little training, and are pushed to work extremely fast–all of which results in a really high percentage of problems for their customers.

Also–you should get into the habit of checking all the fluids under the hood every few weeks, at least. For the time being, refer to your Owner’s Manual for directions on how to check your brake master cylinder and what the level in the master cylinder should be. If it is low, as I strongly suspect, drive to an auto parts retailer and buy a small can of the proper spec brake fluid. Your manual will also list the specification for the fluid.

Incidentally, it is not sufficient to just replenish the brake fluid.
Since brake fluid does not evaporate, a low level in the master cylinder indicates one of the following scenarios:

Your brake pads are worn. As brake pads wear, the calipers extend further, thus drawing excess fluid from the master cylinder. With 41k on the odometer, it is likely that you need new brake pads.
You have a leak in the brake hydraulic system.
Both of these situations need to be explored a.s.a.p., as they constitute a serious safety issue.

If the fluid level is not low, then you need to have the master cylinder checked to determine if the sensor for brake fluid level is defective or if the circuitry for the sensor is flukey.

An excellent post by VDC as always.

I can only add that if the fluid is, in fact, not low you should remove the cover and check that the float is not stuck. And you should definitely get your brakes checked either way. If the float IS stuck at a “low” level, it got down there initially by wear on the pads.

I wouldn’t go to Jiffy Lube to ask directions.

Don’t take their word for it, check it yourself.

I’ve solved this problem for a friend of mine. Iffy Lube had told her that they checked and the fluid level was okay. They hadn’t checked. It was low. Added some fluid kept the light from coming back on.
You also need to check you brake system, because brake fluid doesn’t evaporate. It is low because you either have a leak, or more likely, your pads are worn down.

I took the car to a Toyoata-Scion dealer. They said the brake fluid was low and “black as coca cola.” Plus the break pads were worn. So I had the break pads replaced and the break fluid flushed and replaced.

Thanks for the comments.

…and now you see why we consistently tell people to AVOID Jiffy Lube and all other quick lube places.

If the kids at J-Lube told you that your brake fluid level was “okay”, just imagine what other mistakes they might make under the hood of your car!

Edited to add:
The “black as cola” reference makes me wonder if the kids at J.O. Lube might have topped off the master cylinder with…God only knows what…instead of brake fluid. I sincerely hope that I am wrong!