It comes on after I've been driving for about a 1/2 hour,but the pedal feels the same,a little mushy.I do have a very small leak in the master cylinder,but the fluid level is ok.Will that cause the light to come on?Thanks

 

there is a preasure differance between the front and rear brakes and the idiot light, or the system is picking up on it and setting the light, most likely. look for a leak, if you can't find one you may have a internal leak in the master cylinder seals. there is also a small chance the light is set with no leak.

 

sounds like you need to get the leak fixed.. and work from there..

 

How much does a master cylinder cost?