There are two brake switches near the top of the brake pedal. The power
from the 10A fuse goes through the switch on the right. Battery voltage
comes in the brown wire and supplies power to the purple wire. With the
brake pedal in the rest position, the  button on the switch is pushed in and
12v goes through. You should be able to measure voltage at both wires. When
you step on the brake the circuit is off (with the button out). If the
button is not fully pressed, with the brake pedal up, it may need
adjustment. To remove or adjust, turn the switch counterclockwise.
    The brake light circuit also sends power to the cruise module. So if
your brake lights are on all of the time, your cruise will not work either.