The red BRAKE light on my 2008 Aspen 5.7 Hemi (a Chrysler Durango!) started flashing a few days ago. No symptoms in braking or pedal feel. Park brake is released, and there is plenty of fluid in the MC reservoir. Tested the fluid level sensor with my voltmeter (engine running). It is 4.2V on one pin, and near zero at the other. Don't know if that is correct or not. Looking for a spec.

 

There may appear to be enough fluid but it could be just above the point where the sensor would read it to be low. What can happen is when you either take off or slow quickly the fluid can move inside the master cylinder and cause the light to blink on for a second then when the truck levels out again it will go out.