Emergency Brake Light on Track

[jbug187]

I was up at Lime Rock today and saw the emergency "BRAKE" light come on consistently for ~2 seconds when downshifting from 5th gear to 3rd gear coming off of the main strait. When coming off of the main strait I'm going from full throttle to full brake while heel toeing the downshift with two throttle blips before letting the clutch out in 3rd. RPM is very high while blipping the throttle.

This happened across two ~25 minutes sessions and was consistent. The first time I noticed it I got spooked and checked the emergency brake which was fully disengaged. In the first session I had track mode on with traction control off. The second session I left the nannies on, but still saw the same behavior. Not every downshift was smooth as butter, but some of them were and the light still would come on. After the day was over, I tried some double gear downshifts from 5 > 3 and from 6 > 4 and didn't see any "BRAKE" light come on. Anyone have any idea what's going on? Thanks.

[EndlessAzure]

Check your brake fluid level, or the brake fluid level sensor.

The light will come on if it detects that brake fluid level in the reservoir is too low.


If it is low, do not immediately re-fill your brake fluid. Check that your pads have sufficient thickness first. Brake fluid level and pad thickness are related (less pad, lower fluid level). A fluid leak is unlikely since it seems you still have adequate braking performance, but it may be worth checking for anyway.

[cmiovino]

Can confirm this happened in my WRX years ago and I was confused. Brake fluid was was low. Mine was about halfway between low and full and it came on. It was on and off with the hills we have around here.

I could very much see this happening on track with the g-forces and pad wear if you aren't checking them frequently.

[jbug187]

Originally Posted by EndlessAzure

Check your brake fluid level, or the brake fluid level sensor.

The light will come on if it detects that brake fluid level in the reservoir is too low.


If it is low, do not immediately re-fill your brake fluid. Check that your pads have sufficient thickness first. Brake fluid level and pad thickness are related (less pad, lower fluid level). A fluid leak is unlikely since it seems you still have adequate braking performance, but it may be worth checking for anyway.

Thanks, I'll check the pads and fluid. Can you tell me more about the relation between pads and fluid? As the pads slowly wear down, does the fluid from the reservoir need to compensate in some way?

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[14stu]

Originally Posted by jbug187

Thanks, I'll check the pads and fluid. Can you tell me more about the relation between pads and fluid? As the pads slowly wear down, does the fluid from the reservoir need to compensate in some way?

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The fluid is what moves the brake pistons, so when the pads are worn and the piston has to move farther it takes more fluid from the reservoir.