Ok, This is getting pretty anoying. I have replaced the master cyl & cap, brakes and fluid. I do not have any leaks and I have not had to add extra brake fluid at any time. Light started comming on back in the first cool parts of last fall. I could take the cap off to check the fluid and the light would go out and stay off. Then later on, when it got pretty cold, the light would stay on most of my trip to work, go off by itself, but would come back on once I tapped the brakes.

Last night I replaced the master cyl and cap with a used unit, bleed all the lines in order, and checked function. Brakes worked fine and the lamp did not come on. Thought I fixed it, but lamp came on this morn(36degrees) when I hit the brakes pretty hard.

I HPDE this car and have not had ANY problems with the function of the brakes in three events since the lamp started comming on. The only thing I can think of that might have caused this problem is when I changed brake fluid to ATE Super Blue. Maybe it is messing up the sensor in the cap? Has anyone else had this problem? Thanks, Wes

 

If its a 4th gen lude, I had this problem and it was because there was a rivet in my ebrake that was installed to tightly and it wasnt letting my ebrake down all the way, i read about it somewhere and i looked into it, and thats what happened.