I have a 2002 with 47K. The brake system indicator light came on yesterday. The fluid is at max but I have continuity at the brake system indicator switch. I removed the fluid from the master cylinder reservoir with a syringe. I pulled the float up with a hook I make from small wire. The float did not seem stuck. I re-filled the reservoir with new fluid but the float did not return to the top. I pulled the float up using my hook. I rechecked continuity and confirmed the light was off. I reinstalled the strainer, seal and cap. I confirmed no continuity at the switch. I took the car for a test run but didn't even make it out of the drive before the light came on. Has the float lost it's buoyancy or do you think there is sediment interfering with it? Why won't my float, float?

 

once u got it to float.. did it stay floating.. ?? did u check after you barely got out of the drive way??

 

Yes. Once I pulled the float to the top (after the fluid level was restored) it stayed at the top. No continuity at the switch after install of seal and cap. Just backing out of the drive caused the float to sink enough to turn the light on again.

 

The float has a hole in it allowing brake fluid to fill it internally, and not float anymore.

 

That sounds reasonable. However, the part of the float I see looks like foam. Is there a part of the float I can't see?

 

The only way the float is sold is with a new master cylinder. It's not unheard of to happen, but not very common.

 

I took another look at the float. It appears to be hard plastic, not foam like I first thought. You're probably right about a hole that allowed the float to fill with fluid. Thanks.

 

I have seen this problem in one other S2000. He was told that he had to replace the master cylinder assembly, though it may be possible to find just the reservoir as a used part.

His solution was to disconnect the float MPC. That allows the light to remind you that your parking brake is on and simply requires you to watch the fluid level at regular intervals. One downside is if you get a leak in the system, the light will not come on to warn you anymore.

 

Make that 2 that have had the problem of a non-floating float switch!!!

I had the brake light on the dash after jackong up one side of the car this past week (diff fluid service).

I've learned by now to check the float switch to see if it is stuck and sure enough it was. Simple enough, raised it up with a small screwdriver, replaced the screen and cap and all was good..........for a day! Then the darn light was on again. Popped the reservoir cap back off and the float was sunk! WTH!!!!

Repeatedly raised it (the float - not the car ) 3 times this weekend on a roadtrip. I don't like the implications. I'm not gonna replace a master cylinder because of a stupid float issue. There's gotta ba a better/cheaper solution.......NO?

-Hockey

Just as a heads up: I have NOT serviced the brake system lately. I run ATE Super Blue for fluid, and the fluid level is at the MAX line.

 

I go around dealerships and put an ice pick through them! LOL

This happens but really unusual. The old plastic carb floats would do it too.