Add some brake fluid, Its low. I bet the pads are getting low, As the pads ware the caliper piston travels further and more fluids needed. If it wasnt full to begin with then it will go low and kick the light
or just put some new pads on
01 gtp-big cam e85 dd 78dodge- guzzling fuel 05 cummins- rollin coal
SMGPFC Two Nipple General