Brake Warning Indicator: Description and Operation

The "BRAKE WARNING" Indicator, when lit, alerts the driver to two possible conditions: 1) the parking brake is applied 2) there is unequal hydraulic pressure in the two brake systems.
With the Ignition Switch in "RUN," "BULB TEST," or "START," voltage is applied through the Ga-Trans Fuse and "BRAKE WARNING" Indicator to the Brake Pressure Switch and the Park Brake Switch. When either of the switches are closed, a path to ground is completed and the "BRAKE WARNING" Indicator lights.
The Brake Pressure Switch closes when there is unequal pressure in the two sections of the hydraulic brake system. (This would indicate a pressure loss.) The Brake Pressure Switch remains closed until the cause has been found and fixed. The Park Brake Switch closes whenever the Parking Brake is applied.
The "BRAKE WARNING" Indicator circuit is tested whenever the Ignition Switch is turned to the "BULB TEST" or "START" position. In these positions, the Ignition Switch closes the TAN/WHT (33) wire to ground and the "BRAKE WARNING" Indicator lights.